Translation of N.B.K. Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” (Onychophora), along with remarks about the author and significance of his work Noel N. Tait1*, Ivo de Sena Oliveira2 and Georg Mayer2 1Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 Australia. 2Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, D-34132 Kassel, Germany. *Corresponding author: Email: [email protected]

The basic biology of onychophorans was revealed slowly and controversially during much of the 19th century. Communications were in Latin, French, Spanish, German and English. This information was synthesised in the monumental monographs of Bouvier in 1905 and 1907. However, amongst this multicultural endeavour is a significant Russian contribution by Nikolai Sänger, a student of Professor Leuckart of the Zoological Institute in Leipzig, Germany. Sänger requested a specimen of Onychophora from the Institute’s collection for serial sectioning. This resulted in a detailed account of the anatomy of Peripatopsis capensis. Sänger’s description of the extensive slime glands was the first to recognise them as the hallmark of onychophorans for defence and prey capture, and not the male reproductive system as previously claimed. Based on these morphological observations, he correctly concluded that onychophorans are not hermaphrodites and, furthermore, are “predominantly predaceous” animals. He further appropriately assigned the slime glands and salivary glands to the slime papilla segment, despite the lack of embryological data at that time. Sänger also identified the excretory organs (nephridia) and their openings, although he erroneously assigned them to a dual role of excretion and respiration. Moreover, he highlighted the importance of the position of the genital opening as a diagnostic character, described the ventral/preventral organs as “subcutaneous glandules”, identified the neurilemma enclosing the central nervous system, and recognised “oval holes of different sizes” in each nerve cord that were subsequently demonstrated to represent giant fibres. Of interest to parasitologists, he discovered a larval acanthocephalan encysted within the cutaneous muscles of his specimen of P. capensis, suggesting that onychophorans act as a secondary host for this parasite. Sänger’s memoir concludes with a brief but important description of the first species of Onychophora recorded from Australia, “northwest of Sydney, New Holland”. This species is now known as Euperipatoides leuckartii with a neotype designated from a specific location northwest of Sydney. ABSTRACT

Key words: anatomy, Australia (New Holland), Leuckart, microanatomy, Euperipatoides leuckartii, Peripatopsis capensis, Russian translation, South Africa, velvet worms

DOI: https://doi.org/10.7882/AZ.2021.022

Introduction Although the existence of onychophorans (velvet worms), Russian transliteration) further expanded this knowledge. previously commonly called peripatus, was reasonably well His memoir (Fig. 1A, B) provides further corroboration, known among natural historians of the 19th century, extension and correction of the information provided progress in the establishment of basic aspects of their by these previous studies. It also contains some errors biology was hampered by the availability of specimens of its own that were left for correction by zoologists that for examination. Furthermore, those specimens were followed. While Sänger’s (1871) study was based on a preserved and generally only suitable for obtaining details single museum specimen, use of serial sections to obtain of external features. Despite this impediment, two studies details of microanatomy in situ overcame the problems of of the internal anatomy of onychophorans were obtained dissection of a preserved specimen. Indeed, the revelation from dissections of preserved specimens of Peripatus of the remarkably high quality of histological detail juliformis (Milne-Edwards 1842) and Epiperipatus edwardsii achieved, despite basic fixation and preservation, more [originally described as Peripatus edwardsii] (Grube 1853). than compensated for the laborious task of preparation In a study of Peripatopsis capensis [originally described as and examination of serial sections of such a relatively Peripatus capensis], Sänger (1871; see Zenger 1871 for large animal.

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A) B) Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021

Figure 1. Title pages from the original publication. (A) Title page of the proceedings. (B) Title page of Sänger’s contribution. Modified from Bogdanov and Zenger (1871).

In 1840, Mr Gueinzius provided three specimens of Frauenfeld, such a paramount impression for him was velvet worms from Cape Town, South Africa, for the the observation of living velvet worms. collection of the University of Leipzig in Germany. Here they languished until 1868, when Mr Sänger, a “student” of It was this observation that excluded the slime papillae Professor Leuckart, requested to make one of these valuable as cephalic appendages from the count of ambulatory, specimens available to Professor Bogdanov of Moscow State claw-bearing legs (also referred to as lobopods). Hence, University. This request was granted, provided the specimen the leg count provided by Frauenfeld (1860) was was used for research and the microscope slides retained in accurately given as 17 pairs. Despite this caution, the collection of the Moscow University Museum. the inclusion of these cephalic appendages in the leg count by some subsequent authors remained a A more recent account of onychophorans from South problem. Frauenfeld’s short account of Onychophora in Africa came with the collection of three additional South Africa was included in a report of the scientific specimens during the stay of the Austrian frigate Navara achievements in the natural history of lower animals at the Cape of Good Hope (Frauenfeld 1860). The for 1860 (Leuckart 1862). In this report, Leuckart took Navara was commissioned by the Imperial Academy advantage of this notification of onychophorans from of Sciences in Vienna to circumnavigate the Earth for South Africa to include his own news. “I can add to the scientific exploration from 1857 to 1858. It is quite species known thus far, a new form from Australia with 16 astonishing to read Georg Ritter von Frauenfeld’s obvious pairs of legs” (Leuckart 1862). Thus, Leuckart was in excitement when he discovered several specimens of error for the leg count of 16 pairs rather than 15 pairs Onychophora from under stones at Constantia, on the for the above reason. outskirts of Cape Town. “The most interesting finding was a Peripatus under stones, one of the most peculiar and Frauenfeld’s South African specimens and Leuckart’s deviating forms of animal.” It was even more breathtaking Australian specimen were dealt with by Grube (1866) to witness how the “copious amount of milky white as “Peripatus capensis” and Sänger (1871) as “P. Leuckartii tenacious slime was expelled out of the truncated end of n. sp.”, respectively. From the diagnosis for Peripatopsis the two short mouth feelers [slime papillae] lying under capensis provided by Grube (1866), it was possible to the frontal feelers [antennae]” (Frauenfeld 1860). It is confirm that the three specimens studied by Grube (1866) testimony to the engagement of these animals that, of and the three specimens from South Africa in Leuckart’s all the extraordinary scientific discoveries witnessed by possession were all conspecific (Sänger 1871).

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Nikolai Karlovich Sänger (born 9th October 1841 in He was the first to correct the description of the Moscow; died 31st October 1877 ibidim; Fig. 2A–D) extensive slime glands as the male reproductive organs graduated with distinction from Moscow State University and to record that onychophorans are most likely in 1862, aged 21 years. In 1863, he was appointed as not hermaphrodites as previously reported (Grube the curator/superintendent of the Zoological Museum of 1853; Milne-Edwards 1842). Because of a biased sex Moscow State University, a position he maintained until his ratio towards females, males were only detected when death at the early age of 36. In this position, he frequently sufficient numbers of specimens were examined of a travelled locally within Russia and internationally. This is particular species (e.g., Moseley 1874). possibly why he was attending “classes” given by Professor

Leuckart at the Zoological Institute in Leipzig. During Sänger correctly assigned the slime glands and salivary Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 these travels, he routinely returned with significant glands to the segment of slime papillae (Eriksson and acquisitions for his Museum in Moscow. This may be why Budd 2000; Mayer et al. 2005; Mayer and Koch 2005), he requested a specimen of Onychophora. “Knowing that at that time mostly called “oral papillae” (Evans 1901; Professor A. P. Bogdanov had long wished to have this quite Moseley 1874; Sedgwick 1887; but see von Kennel 1888 rare animal for our Museum” (Sänger 1871). who applied the German term “Schleimpapillen” [=slime papillae]). This is quite remarkable, given that Sänger did Of interest, in the context of this translation, is that not have any embryological data for this assertion. At the Sänger founded the Society of Naturalists among his many same time, he mistakenly homologised the slime glands curatorial duties at the Museum. Furthermore, he was with nephridia of other segments. elected president during the first meeting and became the editor of the “News of the Society of Naturalists”. He He was the first to elaborate on the segmental pores at was responsible for all financial and administrative duties the base of the legs that lead into an extensive and much associated with the publication of the two volumes of coiled tubular system lying in the cavity of the legs and contributions to the Second Congress of Naturalists extending well into the lateral body cavity. The system is held in Moscow, 20th to the 30th August 1869. Professor now referred to as segmental organs or nephridia (Mayer A. P. Bogdanov and N. K. Sänger were co-editors of 2006; Storch et al. 1978). However, he assumed a dual the Sections of Zoology, Anatomy and Physiology. Two function for these organs as excretory and respiratory. papers by Sänger were published in the Proceedings of the The impetus to identify an internal respiratory system, Congress in 1871 titled “On the Baltic representatives of the adaptive to a terrestrial life style, no doubt influenced taxon Gephyrea: Halicryptus and Priapulus” and “Peripatus this suggestion. This same reasoning also resulted in capensis Gr. and Peripatus leuckartii n. sp.” assigning a gas storage function to the tubes of the salivary glands. The respiratory system, consisting of Rudolf Leuckart (born 7th October 1822 in Welmstedt; died tracheae, was identified a few years later by Moseley 6th February 1898 in Leipzig) had gained a distinguished (1874), who had unpreserved specimens at his disposal, reputation throughout Europe as associate professor at the better suited for revealing the air-filled tracheal system. University of Giessen, and later after promotion to professor at the age of 33 years. He took up his call as professor Sänger highlighted the importance of the position of of zoology at the University of Leipzig in 1869. Leuckart the genital opening that had previously been neglected excelled not only in his meticulous approach to research as a distinct diagnostic character. Hence, in Epiperipatus but also in his capacity as a charismatic communicator. edwardsii, which was studied by Grube (1853), the genital His lectures were well attended, which made him an asset opening lies between the penultimate pair of legs, in for universities dependent on fee-paying students. His Peripatopsis capensis behind the last pair of legs and in reputation may be yet another factor why Sänger attended Euperipatoides leuckartii between the last pair of legs. This Leuckart’s classes at the Zoological Institute. character has been used subsequently to characterise species of onychophorans at different taxonomic levels Sänger’s (1871) memoir on the two onychophoran (e.g., Hamer et al. 1997; Reid 1996; Ruhberg 1985). species is divided into two unequal parts. The first is by far the longest and is largely devoted to an anatomical He described the ventral and preventral organs, as small account of one of the three specimens of onychophorans subcutaneous glands, “translucent vesicle(s) seemingly collected from Cape Town, South Africa, for the filled with cells (…) between muscles and skin” (see Leipzig Museum. The subject of the second part is the translation below). These structures and their relevant to Australian zoology, as it described the ontogenetic origin have been a subject of controversy, first Australian species of Onychophora, Euperipatoides as they have been regarded either as metameric units leuckartii [originally described as Peripatus leuckartii] or even ganglion anlagen of the ventral nervous system (Fig. 3). This was of zoogeographical importance as (Eriksson and Stollewerk 2010a, 2010b; Pflugfelder 1948; it included Australia with the two other southern but see Mayer et al. 2015 and Mayer and Whitington continents, Africa and South America. Given the 2009) or, alternatively, as attachment sites of segmental importance of Sänger’s (1871) work, we summarise his limb muscles (Oliveira et al. 2013, 2019). major achievements in the following.

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Figure 2. Photographs of Sänger and his grave. (A) Portrait of Sänger at a young age (from Bogdanov 1888). (B) Portrait of Sänger from the time when he was superintendent of the Zoological Museum of Moscow State University (from Dvadtsatip͡ iatiletie͡ Muzeia͡ prikladnykh znaniĭ v Moskve 1898). (B, C) Sänger’s grave (indicated by white arrow in C) and tombstone (detailed in B) in Section #4 of the Vvedenskoye Cemetery in Moscow. Images courtesy of the staff of the Moscow City Municipal Funeral Service and the State Budgetary Institution “Ritual”.

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Sänger further stated that, “oval holes of different sizes are The second part of Sänger’s (1871) memoir is devoted to noticeable in subsequent sections” of the ventral nerve cords. the description of a specimen of Onychophora collected This was most probably the recognition of giant fibres in by Dr J. Pessler, who was a student of Professor Leuckart the central nervous system (Schürmann and Sandeman during his time in Giessen long before moving to Leipzig. 1976). Sänger also described the prominent neurilemma The specimen was collected from New Holland (now enclosing each brain hemisphere and nerve cord (Mayer Australia) northwest of Sydney, “So far, no other species and Harzsch 2007; Schürmann 1987). has been known from New Holland and the one obtained from there shows some quite considerable differences” (see the Based on his purely morphological observations, Sänger translation below). About the etymology of the species, he

correctly and prophetically concluded that onychophorans writes, “The species is described based on a specimen belonging Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 were “predominantly predaceous” animals. to Professor Leuckart and, upon his agreement, I suggest to name it Peripatus Leuckartii”. This species is now known As a parasitologist, interested in gut parasites, Leuckart under the full scientific name “Euperipatoides leuckartii would have been pleased that Sänger identified a larval (Sänger, 1971)” (see Oliveira et al. 2012a). Due to the acanthocephalan, encysted within the cutaneous muscles ravages of World War II and its aftermath, the holotype in of his sectioned specimen. Acanthocephalans are gut Leipzig has been lost, but a neotype has been subsequently parasites of vertebrates (primary hosts) with larval stages designated from a specific locality, Mt Tomah northwest of occurring in arthropods (secondary hosts). The existence Sydney (Reid 1996). of acanthocephalans as parasites in onychophorans was confirmed much later by the discovery of three larval Perhaps the most important diagnostic character, described acanthocephalans in the body cavity of Peripatopsis by Sänger to distinguish E. leuckartii, was the number of clavigera (Hofmann 1988). This is unusual, to say the legs. Initially it was stated as, “15 pairs of legs; the first pair least, with the terrestrial onychophoran playing the role of without claws and 14 pairs with claws”. This somewhat a secondary host. As such, the discovery of the terrestrial ambiguous statement could suggest that the first pair of primary host, presumably a predator of onychophorans, legs were the cephalic appendages, and the remainder would be of considerable interest. the ambulatory legs or lobopods. This is without doubt Sänger’s intention as he compares E. leuckartii with Sänger clearly distinguishes the onychophoran lobopods Peripatus brevis (de Blainville in Gervais 1837) a species (with claws) from parapodia of polychaetes (with setae) described from South Africa with 14 pairs of lobopods, but and arthropodia of arthropods (with joints) and he now considered a nomen dubium (or even a synonym of concludes with some interesting thoughts regarding the Peripatopsis capensis; see Ruhberg 1985). To confound this phylogenetic position of Onychophora, which has not issue further, the summary diagnosis is given as, “Species been entirely settled even today (Giribet and Edgecombe with 15 pairs of legs; genital opening between legs of the last 2017; Martin et al. 2017a, 2017b; Mayer et al. 2013). pair; legs equipped with three sole pads – one long arcuate one and two short straight ones; found in New Holland”.

Figure 3. Photograph of a living specimen of Euperipatoides leuckartii (Sänger, 1871) from the type locality northwest of Sydney.

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This latter diagnosis would not have caused the taxonomic (Dendy 1895), and Joseph James Fletcher, Secretary of confusion that followed as to whether E. leuckartii had 14 or the Linnean Society of NSW in Sydney (Fletcher 1895), 15 pairs of legs because the reader would have reasonably both concerned with documenting the onychophoran assumed that the 15 pairs of legs were ambulatory legs and fauna of Australia. These two zoologists were often in did not include the cephalic appendages in the count. In quite acrimonious dispute concerning their observations any event, the confusion was settled when the specimen and opinions of the biology of Australian Onychophora was re-examined in the collection of the Zoological (see Tait et al. 1990 for further details). Dendy (1895) Museum in Leipzig by Dendy (1906). After his plea for a quoted that the species is “found in New Holland, north- German zoologist to inspect the specimen was unfulfilled, west from Sydney” and possesses “(f)ifteen pairs of legs,

he travelled to Leipzig and appraised the specimen himself one pair without claws, fourteen with.” Fletcher (1895) Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 (Dendy 1906). He clearly found it to have “fifteen (15) published the translation of Sänger’s (1871) diagnostic pairs of walking legs and a pair of oral papillae” (Dendy section in its entirety [but note that Dendy eventually 1906; note that slime papillae is the term now coined for made the journey to Leipzig in order to reinvestigate the paired cephalic appendages: Eriksson and Budd 2000; Sänger’s type specimen himself (Dendy 1906)]. Oliveira et al. 2012b). Recognition of the work of Nikolai Karlovich Sänger has Apart from this present publication, the only translation been much overlooked due to language and the obscurity of Sänger’s (1871) memoir into English was confined of the publication, although a French translation has to that part relating to the diagnosis and description of been available since 1900 (Anonymous 1900). Bouvier Euperipatoides leuckartii as this was of particular interest probably edited this translation, whereas his colleague, to Australian zoologists, and in particular those interested Professor Nicolas de Zograf, from Moscow, was responsible in onychophorans. One of these zoologists was Professor for finding the translator whose name unfortunately Walter Baldwin Spencer, first professor of biology at the has not been recorded (Bouvier 1900). The French University of Melbourne, Australia (1887 – 1929). He translation contains only one panel with a selection of graduated from the University of Oxford in 1884 where a few images that had been lithographically reproduced he came under the influence of Professor Henry Nottage from Sänger’s (1871) original work. Moseley. Moseley was the naturalist on board the Challenger Expedition (1872 – 1876). While the Expedition was berthed Here we provide the first English translation of the entire at the Cape of Good Hope, South Africa, Moseley collected memoir as presented in the Proceedings of the Second Peripatopsis capensis and was the first to dissect fresh Congress of Russian Natural Scientists in Moscow 20th specimens and accurately record details of their internal to 30th August 1869. In editing this translation, we have anatomy (Moseley 1874). At the time, Moseley was unlikely modified the punctuation to shorten the excessive length to have had any knowledge of Sänger and his study of the of sentences. Otherwise, we have kept as many details as anatomy of a single preserved specimen of P. capensis. possible, including the passive voice, in order to retain a flavour of the times and the language. Comments The Challenger also visited Australia. As a consequence, and amendments were included only where absolutely Moseley encouraged Spencer to research there, which necessary. These comments as well as our additional he did, spending his working life of 42 years at the translations of texts from German, French and Latin, University of Melbourne. On a visit to the UK, he as quoted by the author, are highlighted in italics and arranged the translation of the section of Sänger’s enclosed in square parentheses. The original page numbers (1871) work relating to the description of E. leuckartii. are provided as secondary headings. To avoid confusion, A copy of this translation was given to Arthur Dendy, we renumbered Sänger’s (1871) footnotes consecutively. lecturer in biology also of the University of Melbourne

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Translation demands its own class related to gastropods.”] The author proposed to establish for it a separate class of mollusks Page 236 named Polypoda. PROCEEDINGS OF THE SECOND CONGRESS Another specimen of Peripatus, found by Lacordaire in OF RUSSIAN NATURAL SCIENTISTS Cayenne, was described by Audouin and Milne Edwards2 IN MOSCOW, and assigned to free-living ringed worms – annelides TAKEN PLACE errantes. According to the description, the worm was from the 20th to the 30th August 1869 found “sous des bois pourris, enfoncé dans la vase sur les bords st th [from the 1 to the 11 of September Gregorian date] de la rivière d’Approuague et à trois lieues de son embouchure. Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 PART TWO Les eaux etaient d’une nature saumâtre” [translation from MOSCOW French: “under rotten wood, sunk in the mud on the banks of 1871 the Approuague river, three leagues from the river mouth. The waters were brackish in nature”]. Page 237 PROCEEDINGS K. Moritz3, who provided specimens for the Berlin OF THE SECOND CONGRESS Museum that he found in Colombia in the vicinity of Lake OF RUSSIAN NATURAL SCIENTISTS Valencia and afterwards in the Valleys of Aragua, argued IN SECTIONS OF against this locality record of Peripatus. He found them ZOOLOGY, ANATOMY AND PHYSIOLOGY always on land – in grass under stones or under pieces of Edited by Professor A. P. Bogdanov and N. K. Sänger wood. At first sight, the appearance of the worm made on him the impression of a slug, since white slime, with which Page 238 the animal was quickly covered, reinforced its putative PERIPATUS CAPENSIS GR. similarity to naked slugs (Limax). One of the specimens and collected by Moritz was used by Wiegmann PERIPATUS LEUCKARTII N. SP. by N. SÄNGER Page 240 for a detailed description of external features4. Recognizing Page 239 the affinity of this animal to free-living ringed worms, Transitional forms, whose features do not fit into Wiegmann pointed out that it should be considered as a the framework of the already established system, are transitional form, linking the ringed worms to articulated condemned to a more or less prolonged transfer from class animals [representatives of the Articulata] or animals with to class and order to order. Peripatus, a curious animal of articulated limbs [i.e., arthropods], more precisely with the tropical countries [note that onychophorans occur also in class of millipedes (Myriapoda). Gervais, who almost at the temperate regions], although well known to zoologists but same time described together with Blainville a new species extremely rare in zoological museums, experienced and of Peripatus from the Cape of Good Hope under the name still experiences the same fate. Initially described as a slug, Per. brevis, goes even further. [Note that Peripatus brevis it was afterwards recognised as a worm, later as a millipede may be considered as either nomen dubium or a synonym [note that it had never been recognised as a millipede but of Peripatopsis capensis (see Ruhberg 1985). If the latter rather a link between annelids and myriapods]; thereafter it scenario is assumed, P. capensis has to be declared as nomen was again described as a worm belonging to this or other protectum and P. brevis, which is an older name, as nomen group, or placed as a distinct class among the animals with oblitum.] In the article “Sur le genre Peripatus”5 [correct articulated limbs [i.e., the arthropods]. spelling of the title: Sur le genre péripate], he established for this animal a distinct class of arthropods [sic; note Lansdown Guilding was the first to find this animal in the that Gervais (1838) in fact established the malacopodes as forests of St. Vincent and wrote describing it1: “Inter plantas intermediate between the myriapodes and the chaetopodes]. a me lectas ad radices montis immensi ‘Bon Homme’ unicum exemplum attonitus forté detexi… Subregnum Mollusca hocce The first but quite limited information on the internal genere paradoxico multum perturbatur… Genus incertae sedis anatomy of Peripatus was provided by Milne-Edwards, classem propriam, gasteropodis affineum reposcit, quae pedibus who investigated the initially described species Peripatus multis lateralibus ditinguitur.” [We have corrected some juliformis6. Blanchard who added to both known species misspellings and typing errors in this quotation. Translation 2 Annal. des Scienc. natur. T. XXX. 1833. P. 411. from Latin: “Among the plants I gathered at the foot of a large 3 C. Moritz. Noch einige Worte über Peripatus Guild. Archiv für hill called Bon Homme I spotted a specimen by chance and to Naturgeschichte. V Jahrgang 1839. H. 2. S. 175. my surprise… This paradoxical genus has greatly altered the 4 A. Wiegmann. Einige Bemerkungen über Guilding’s Peripatus. Archiv für subkingdom Mollusca… The genus with uncertain position Naturgeschichte. III Jahrgang. 1837. H. 2. S. 195. (incertae sedis), which is distinguished by its many lateral feet, 5 Ann. franc. et étrang. d’anatom. T. II. 1838. P. 309. 1 Lansdown Guilding. An account of a new genus of Mollusca. Zoolog. 6 Note sur le Peripatus juliformis. Ann. des. scienc. natur. 2. Ser. Tom. XVIII. Journ. 1826. II. P. 444. 1842. P. 126.

Australian 2021 Zoologist G Tait et al. two additional ones, namely P. Blainvillii [note that the it either as a true millipede or even as a representative correct spelling is “blainvillei”; note also that Metaperipatus of the separate class of Arthropoda, following Gervais. blainvillei is a nomen dubium (Oliveira et al. 2012a)] and P. Edwardsii (the latter one being a synonym of P. juliformis Examples of these latter classifications provide sufficient described by Audouin and Milne Edwards in 1833), evidence for how little consensus there is for the place of reported some data on the structure of P. Blainvillii7 Peripatus in the scientific system. However, this is justified [sic], but these investigations, for which badly preserved by the peculiar features in its organization that completely specimens were used, do not contain any significant segregate it from all other known forms; the existence of information and are quite superficial. a differing number of soft legs with two strong claws at

their tips in different species, the presence of large, fleshy, Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 Milne-Edwards introduced an anatomical feature to the somewhat ringed antennae on the head, the development of classification. Having detected considerable peculiarities two sharp, paired jaws in the mouth, which are surrounded in the arrangement of the nervous system, he proposed a by fleshy lips, and point ventrally, the strong musculature of separate group, Pleuraneura, to contain Peripatus among the body, the many special features of internal organization the ringed worms. with regard to the nervous system and the reproductive organs, and, finally the ability to produce live young and The more recent work of Grube8 should be considered their terrestrial lifestyle. All this, taken together, makes it as the only comprehensive and thorough investigation of indeed difficult to determine the closest relationship to any the anatomical organisation of Peripatus. The researcher known group. German researchers, assigning Peripatus to had a considerable number of specimens at his disposal, worms following Grube, used only estimations, analogies which were collected by Dr. Karsten [or “Carsten”?] in rather than direct observations. As arguments they consider, Venezuela9. I will often refer to the contents of this work for example, the fact that the nervous system represents a in presenting my observations; here I only note that Grube type close [highlighted by the author] to its organisation in placed Peripatus in a separate order of ringed worms10, worms and consists of cephalic ganglia and two ventral which he named Onychophora (claw-bearers) [italicised cords, widely [highlighted by the author] separated from each by Sänger], in reference to the characteristic presence of other but linked by commissures. Further, that the jaws paired claws on the tip of each leg and, based on arming the short proboscis of Peripatus, resemble [highlighted by the author] the shape of the jaws of some ringed worms; Page 241 that the legs should not be related [highlighted by the author] his accumulated anatomical data, which thereafter to the jointed legs of articulated animals [Sänger apparently confirmed his opinion about the assignment of this means arthropods here], but that they rather correspond group to the Annulata [at that time apparently Annulata [highlighted by the author] to the soft lateral appendages of was a taxon of Articulata, nearly equivalent to Annelida, ringed worms, but differing considerably [highlighted by the including marine annelids, Gephyrea (Echiura, Sipuncula author] from them in that they do not carry setae on their and Priapulida), Gymnotoma (Archiannelida), earthworms, tips but possess claws instead. All this indeed complies with leeches, and others] numbering five orders accepted analogy, whereas among these there is not a single feature by him. This opinion found its way into some recent uniting this animal with worms. One can speak about classifications. Furthermore, Carus kept the name of the resemblances, but in the organisation of Peripatus there is order, which maintained its assessment given to it by not a single formation that would iterate what we know Grube. In the last edition of his comparative anatomy, from worms and this way ultimately clarify the question. Gegenbaur widened the limitations of this group and, after segregating Onychophora from the class Annulata, Page 242 considers them as a separate class of worms, parallel By chance, I was able to carry out an anatomical and equal in the status to other classes, including investigation of this extremely curious form during my Gephyrea [Echiura, Sipuncula and Priapulida], Tunicata, classes at the Zoological Institute of Professor Leuckart Enteropneusti, Rotatoria and others. Only Quatrefage in Leipzig. Three specimens of Peripatus were found in still refuses to accept Peripatus as a worm and at the end the Leipzig Museum among the insect larvae that were of his last comprehensive systematic book on worms collected for the Museum by Mr. Gueinzius in 1840 in entitled “Animaux á tort places parmi les annelides” places the surroundings of Cape Town at the Cape of Good this worm on first place between enigmatic forms. Not Hope. Knowing that Professor A. P. Bogdanov [Sänger’s convinced about the analogies, he is willing to consider co-editor of the Proceedings] had long wished to have this 7 Sur l’organisation des vers. Ann. des Scienc. natur. 3 Ser. T. VIII. 1847. P. quite rare animal for our Museum, I asked Professor 137. Leuckart to give me one of the found specimens. But 8 Ueber den Bau von Peripatus Edwardsii. Müller’s Archiv für Anatom. u. he consented only on condition that I use the provided Physiolog. 1853. P. 322. specimen for research and preserve the microscopic 9 One of these specimens is in the Zoological Museum of Moscow slides of this specimen for the Museum. University. 10 Die Familien der Anneliden. Archiv f. Naturgesch. Herausg. v. Troschel. After agreeing with this condition, of course, I could XIII Jahrgang. H. 2 and 3. S. 275 and 281. not expect that the study of a single specimen would

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Plate XII from Sänger (1871). Note that the individual captions to figures 1–27 are provided above in the last section of the text entitled “Explanation to Illustrations”.

Australian 2021 Zoologist I Tait et al. lead to some kind of satisfactory result, but nevertheless Hence, in P. Edwardsii with 29–30 pairs of legs the genital I was lucky to obtain from this investigation some opening lies between the penultimate (second last) pair of preparations that would expand the existing information legs, in P. capensis it is located behind all legs close to the about Peripatus and to a certain degree serve to clarify the anal opening. In the new species of Peripatus from New question about the position of this animal in the system. Holland [historical European name for mainland Australia], on which I will say a few words at the end of the article, the The specimen, which served as material for this work, genital opening lies between the legs of the ultimate pair. turned out to belong to the species Peripatus capensis These differences are sufficiently distinct and conspicuous Grube, which was first described by Grube two years ago to use them for the diagnoses of the different species.

among the ringed worms brought by the expedition of Moreover, these differences in the more or less distantly Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 the frigate Novara (Reise der österreichischen Fregatte positioned openings at the posterior end of the body, Novara um die Erde in den Jahren 1857, 58 and 59. without any doubt, are reflected in the arrangement or Zoologischer Theil. II Band. Anneliden. Wien. 1867). shape of internal organs in this part of the body. Frauenfeld found three specimens of this species under stones by Constantia [suburb of Cape Town located south of Since the Leipzig specimens of P. capensis were in good the Kirstenbosch National Botanical Garden — nowadays one condition, despite the long preservation in ethyl alcohol, of the most prestigious suburbs in South Africa] at the Cape it could be confirmed that in the colour of the tegument of Good Hope. The diagnosis of this species as well as they completely corresponded to the specimens described the remarks made by Grube in his description completely by Grube. Their dorsal side is brown, brighter on the sides match the characteristics of the three specimens found and with a dark thin line running in the midline. This in the Leipzig Museum and collected 28 years ago [based colour depends on the roundish papillae of the skin – tiny on this and the year of collection, we conclude that Sänger black ones and large yellow-red ones. While there are no already worked on his manuscript in 1868]. As with Grube’s red papillae along the dorsal midline, they are abundant specimens, these three specimens showed some variability on the lateral sides. The ventral side appears lighter; the in size. The largest of them measured 27 mm in length, papillae covering it are flatter, more delicate and arranged the other one, which was used by me for research, 24 in transverse rows, not entirely parallel but curved, mm, and the third one 21 mm. These dimensions closely especially between each pair of legs. Along the midline correspond to sizes reported by Grube. All three possessed between each pair of legs, a distinct small depression is 17 pairs of legs, equipped with claws and three transverse recognised appearing as a black dot [ventral/preventral pads forming something like a sole at the underside of the organs]. Regarding the legs, their conical body is soft, in leg. Apart from the 17 pairs of clawed legs, in all of them the upper part similarly covered with papillae, in the lower there was a vestigial pair of legs without claws belonging to part with flatter elevations of the cuticle. The sole of these the mouth segment [slime papillae sensu Eriksson and Budd legs consists of three stiff blackish pads covered with hairs (2000)]. In one specimen, Grube additionally saw claws (Plate XII, Fig. 5). The outermost pad, which is at the at the posterior end and therefore suggested this specimen same time the smallest, possesses along the outer ridge had 18 pairs of clawed legs, considering these claws as a a row of short, stiff hairs resembling bristles. The clawed rudimentary posterior pair of legs. Likewise, amongst the part of legs has an inverted conical shape and is covered Leipzig specimens one possessed these distinct posterior with large papillae, always uniformly arranged. I made claws, only with the difference that Grube observed this a drawing of this part using considerable magnification peculiarity in the smallest specimen (20 mm), whereas in order to show the arrangement of these papillae in P. here the posterior claws were found in the largest specimen capensis. On the very tip of this part, where two strongly (27 mm) (Plate XII, Fig. 4, x). I do not believe though that curved claws are located, there are three large round these claws should be considered as a rudimentary pair of papillae, as a consequence of which this tip of all legs legs as there is no hollow cone corresponding to the body appears triangular: one papilla is situated anteriorly, two of the leg, the claws are situated directly in the bumps of posteriorly [this is an error, as it should read “two papillae are the skin and there are not two of them situated anteriorly, one posteriorly”]. Page 243 Page 244 but one on each side. Considering their position on each Apart from papillae at the base of the clawed part of the side of the genital opening, they appear as tools required leg, two hypodermal vesicles are recognised at the bottom for copulation [sic]. In the two other specimens, there was that are situated toward the two longitudinal furrows. not the slightest trace of such claws. In all specimens, the Apparently, these vesicles have outer openings and it anal opening is situated on the tip of the posterior end of seems very likely that during the contraction of the leg the body, the genital opening nearby on the ventral side. these hypodermal vesicles expel some sort of fluid, which flows along the furrows to the claws. The position of the genital opening, which has been neglected thus far in the diagnoses of Peripatus species, in In Figure 7 (Plate XII) I have illustrated a large papilla my opinion represents a fairly distinct systematic character. from the surface of the body. Such papilla represents a dome-shaped elevation of the skin, on top of which

Australian J Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” a detached spherical part is located carrying an apical the feature on which the issue of the affiliation of Peripatus pointed and stiff bristle. In the entire elevation, to the worms can be regarded as ultimately resolved. subcuticular, multigranular cells are clearly recognisable, which on the surface correspond to chitinous conical, Previous researchers already saw external openings at the leaf-like formations [scales] covering the entire body and bases of legs on their ventral side. In the description of giving it such a peculiar form. As mentioned above, the Peripatus11, Audouin and Milne Edwards stated about the entire body is covered with such papillae. legs: “…à leur face inférieure une ouverture, qui parait ètre analogue à celle, que nous avons déjà signalée dans le At the anterior end of the body, in the first or frontal genre Hipponoé” [translation from French: “…on the ventral

segment, large cylindrical ringed appendages or antennae part, there is an opening that may be considered analogous Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 are situated, at the basis of which on the dorsal side to the one already pointed out in the genus Hipponoé”; there are two distinct eyes. The ventral mouth opening note that Hipponoé belongs to the polychaete taxon is surrounded by a short fleshy proboscis consisting of Amphinomidae]. Wiegmann confirmed the statement of delicate radial pads or folds [oral lips]. In the middle of the French researchers, while Grube denied the existence this proboscis a wedge-shaped fleshy protrusion [tongue] is of openings and considered them to be simple depressions recognised, directly under which two jaws are located on in the tegument. The openings in fact do exist and each side, the upper or anterior of which is thin, curved serve indeed as exit openings of the segmental organs. and pointed, the lower or posterior of which is thicker There are branched tubules [Sänger’s interpretation of the and with a long, curved tooth and three smaller toothlets nephridial duct as a branched structure was probably due [denticles] pointing inside. Similar to the surface of the to its convolutions] in spaces between subsequent pairs of proboscis or outer lips forming it, little chitinous cones are legs, next to the nerve cord and under the mesenterial recognised on the inner wedge-shaped protrusion [tongue] wall separating this cord from the inner body cavity. They inside the mouth, which terminates in a blunt apex. It is are often quite numerous, running toward the leg and very likely that these are gustatory papillae. fusing to a common tube with glandular walls, which then bends and passes from the body cavity into the leg The inner organisation of P. capensis in principle resembles cavity. Here, the glandular tubule is accompanied by what has been known about the organisation of P. three other tightly adjacent canals with thin walls (Plate Edwardsii, thanks to the work of Grube that has already XII, Figs 17 and 18). They can be followed inside the been mentioned by me. In the majority of cases, my body cavity as well as for a considerable length of the preparations confirm all those anatomical data that have outgoing glandular canal inside the leg (Plate XIII, Figs been gathered in this investigation and I would like to 21–25, so and sot [“so” and “sot” are abbreviations used supplement them only in some respects. in the figures]). But thereafter they disappear and the outgoing canal becomes simple, initially still quite thick, As far as I can judge, the most substantial addition I can finally thin tubule directed downwards, the walls of which make is that, with the help of transverse sections through apparently display an inner epithelium. This tubule opens the legs of the worm, I found distinct branched glandules directly outside via the above-mentioned opening. In the opening to the outside [their branched structure claimed first three pairs of clawed legs, I was unable to see these by Sänger contradicts the German description hereinafter as glandules in the obtained slides, but in the subsequent loop-shaped]. In my opinion, these should be recognised pairs they were everywhere more or less distinct. It is as segmental organs (schleifenförmige Exkretionsorgane) difficult to say anything about the role of these segmental [translation from German: “loop-shaped excretory organs”] organs, without having carried out adequate observations the presence of which represents a common feature on living specimens. Every suggestion would be more or of the majority of ringed worms. Carus says in the less a guess. Most likely, they [the nephridia] serve either general description of worms on p. 430 of his zoological reproductive purposes or for breathing or as excretory manual: “Schleifenförmige Excretionsorgane sind nur organs. Considering the composition of these organs bei den Onychophoren (Peripatus) noch nicht gefunden of a dual type of tubule, glandular with thick walls and worden, am genauesten untersucht sind sie bei den membranous thin-walled, with a single common outgoing Lumbricinen und Hirudineen.” [Translation from German: canal, I readily believe that their role might be dual in “Loop-shaped excretory organs have as yet not been identified those regions where they have the described shape. They in onychophorans (Peripatus); they were studied best in may serve as excretory and at the same time as respiratory lumbricines and hirudineans.”] I believe that this gap can organs. It appears likely to me that right through the thin- be most likely closed by the glands identified by me in P. walled canals, the exchange of gases occurs and that blood capensis and, therefore, can come into immediate contact with them. Page 245 Page 246 indicate an even greater commonality of this formation If such an assumption were to be confirmed, on the one among the worms. The existence of these glandules [in hand, the respiratory process could be clarified, which has the literature variably called segmental, excretory, renal or been completely neglected by previous researchers, while, nephridial organs, or simply nephridia] in Peripatus provides 11 Ann. d., scien. Nat. T. XXX, 1833.

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Plate XIII from Sänger (1871). Note that the individual captions to figures 28–35 are provided above in the last section of the translation entitled “Explanation to Illustrations”.

Australian L Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” on the other hand, we would obtain an example of a the lateral cavity from the oesophagus, and further on peculiar adaptation of segmental organs to a new function close to the digestive tract in the main body cavity. Part caused by an aerial, terrestrial lifestyle of the worm, and of the wall of this tube is shown in figure 16. Prominent we would recognise in these organs a kind of prototype external longitudinal muscles are clearly recognisable of future tracheae of articulated animals [arthropods are within it, as well as transverse muscles located in the probably meant]. middle and, finally, epithelial glandular cells pointing internally. The same dark formless matter, which was not Homologous or essentially homodynamic formation with stained with carmine and is located in the outgoing canal, respect to the described segmental organs in the body of partially continues to fill the inner, fairly wide cavity of

Peripatus apparently also exists in the first [leg-bearing] these glandular tubes. The organisation of their walls does Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 segment [note that Sänger considered the slime papillae as not change throughout the remaining length. the first pair of (clawless) legs]. On the most anterior pair of legs [i.e., the slime papillae], which do not possess claws Initially these tubes of both sides run fairly symmetrically, on the tip and appear somewhat rudimentary, an opening but they are shifted to one side further down, without is recognised via which also open peculiar glandules being fastened to the body wall in the specimen studied [slime glands]. They are considerably more developed by me. At the ninth pair of legs, each tube, still straight than the remaining segmental organs of other segments and unbranched, gives rise to lateral branches and and occupying considerable space in the body cavity of disintegrates into a considerable number of thin glandular the worm, branching along the entire digestive tract. tubules, which at considerable extent fill in the entire [Apparently, Sänger considered slime glands as serial homologs space between the digestive tract and the dorsal wall of nephridia.] After finding P. capensis, Frauenfeld stated of the body. Each branch (Plate XIII, Fig. 24, gs [“gs” is that upon the first contact with the worm, an abundant an abbreviation used in the figure]) represents the same fluid mass of milky colour and sour [highlighted by the voluminous walls, although their cavity becomes very author] smell12 pours out via these anterior legs [slime inconspicuous and shines through as a narrow canal. papillae], which he called tentacles. While investigating In my specimen, these branches extend to the region P. Edwardsii, Milne Edwards and subsequently Grube including the 16th pair of legs, suggesting that the most described glandules that open via these legs as male genital posterior branches of these glandules extend to the organs, thus considering Peripatus as a hermaphrodite. posterior part of the body cavity.

While describing P. capensis, Grube agrees that the It is exactly this branched glandule [slime gland] that M. observation of Frauenfeld does not support the assumption Edwards and Grube regarded as the male genital organ, of the excreted fluid as sperm and, consequently, the but it is hardly possible to agree with such a conclusion. glandules themselves as the male genital organs, but I believe that the prominent muscular wall, the slimy apparently, he does not refuse his previous opinion, only excretory product that does not stain with carmine, the sour regarding the question as not entirely resolved. Based [highlighted by the author] reaction of this substance and the on transverse sections, I could convince myself that a fact that it is ejected immediately by touching the worm wide outgoing canal opens into the cavity of the leg speaks against the assumption that this glandule [slime [slime papilla], which lies in the lateral part of the mouth gland] represents the male genital organ, especially since segment near the mouth cavity and the nerve cords essentially no evidence exists in favour of this assumption. emanating here from the brain (Plate XII, Figs 10 and 12). This outgoing canal is segregated from the remaining Neither M. Edwards nor Grube, who expressed this more body cavity by a muscular septum. Its walls appear quite or less unfounded suggestion, were able to indicate an thick and are lined by an internal epithelium. In my analogous example among the worms for such a position preparations, the cavity of the canal is filled with dark of the male genital organs. They were forced to take it matter, which carmine does not stain. from another division of animals, in order to make this explanation more likely. Grube states in the following In further posterior transverse sections, this spacious canal words about the role of this genital glandule: “dessen disappears. A narrower tube with rather muscular walls is Bedeutung als solches nach dem, was ich gesehen, recognised in its place (Plate XII, Figs 14, 15, 16 gs [“gs” kaum mehr zweifelhaft ist — eine Umwandlung, die is an abbreviation used in the figures]), which previously was wir wenigstens in einer sehr ähnlichen Weise bei den located laterally behind the septum separating Crustaceen und Arachniden wiederfinden, bei jenen, indem ein Fusspaar des Hinterleibes, bei diesen, indem Page 247 die Maxillentaster zur Uebertragung des Samens dienen.” 12 Moritz (Arch. F. Naturg. V. 1839 p. 175), who like Frauenfeld saw living [Translation from German: “its significance as such, from specimens of another species of Peripatus, reports that slime secreted what I have seen, can hardly be doubted any longer — a by the worm is ejected in several jets from the sides of the body (in transformation, which we find at least in a very similar fashion vielen Strahlen von den Seiten des Körpers) [German] and, when ejected, is absolutely colourless and, hence, hardly seen. Only upon in crustaceans and arachnids, in which a foot pair of the hind contact with air, it subsequently becomes milky. He considers Guilding’s end serve in these as the maxillary palps for the transfer of expression “ab ore respuit” as certain mistake. sperm”.] The assumption of hermaphroditism in Peripatus

Australian 2021 Zoologist M Tait et al. was also born accidentally and is also devoid of any body cavity [i.e., the lateral sinus]. In fact, in all transverse satisfactory reasons. sections it can be recognised that the body cavity is subdivided by septa into three: a large to median division I believe that it would be fully justifiable to ask the [central sinus], in which the wide digestive tract and the question: Is Peripatus indeed a hermaphrodite? accompanying, above-described branched glands of the first segment lie; and two lateral symmetrical divisions [lateral The existence of specimens that, while corresponding in sinuses], in each of which are situated, the nerve cord close all other to the ventral and median part of the body, dorsal and lateral to it the described structure at the lateral body wall,

Page 248 and in the interspace between it and the nerve cord those Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 features, differ by the presence of claws at the posterior body segmental glands [nephridia] that pass from here to the end and generally the insignificance of the investigated cavity of the leg and open outside. The name lateral vessel number of specimens absolutely justify this question and it given by Grube to this structure, in contrast to the dorsal might well be that these worms will have to be recognised blood vessel, cannot be upheld, as by following subsequent as dioecious. [This assumption was confirmed three years sections one is easily convinced that this organ [i.e., the later by Moseley (1874) who detected males and females and salivary gland] extends only along the sides of the anterior thus refuted the idea that onychophorans are hermaphrodites.] half of the body rather than the entire body, as Grube states; apart from this, it comprises along its entire length Assuming this as quite likely, I propose that the described glandules [i.e., the slime glands] are homologous with Page 249 the segmental organs [nephridia] of the other segments, a considerably wide inner cavity and exceeds sometimes serving only for the secretion of slime, and that their threefold or fourfold the thickness of the nerve cord. The muscular walls promote the ejection of this slime and their organ indeed tapers somewhat toward each end and it considerable development can be explained exactly by the seems to divide into separate blunt and blind lobes near need of secretion in very large amounts. the posterior end. In regard to the anterior end of this organ, I am ready to assume its direct association with the In regard to these just described branched glandules, first pair of legs [i.e., the slime papillae] and, consequently, in the body of Peripatus another structure exists, which with the glandules that have been so far considered as the has received no attention thus far. The existence of this male genital organs. [Note that Sänger’s assignment of slime novel structure [i.e., the salivary gland], also of glandular glands and salivary glands to the slime papilla segment has organisation, even more complicates the question about been confirmed by subsequent embryological studies including, the role of large internal glands in the body of our worm. e.g., Sedgwick (1887), von Kennel (1888), and Evans The structure, which I mean, was recognised by Grube, (1901). However, other studies consider the slime glands as but described by him absolutely not in the way, which derivatives of the crural glands that occur in specific trunk is presented by my preparations. In figure 12 of his first segments in males (rarely in females) of various species and plate, Grube illustrates a narrow canal (vl), which lies on may be involved in the secretion of pheromones (Barclay et al. each side of the body together with the nerve cord in a 2000; Reid 1996; Storch and Ruhberg 1993).] I was unable gutter-like depression, separated from the main cavity by to obtain a convincing section, but in the region where a septum. This is what Grube says about this canal: “über the oesophagus ends and the wide digestive division of dessen Bedeutung ich nicht ins Klare kommen kann; ich the gut begins and the muscular tubules of the branched will ihn den Seitenkanal [highlighted by the author] nennen. glands pass from the lateral part of the body cavity to Er durchläuft die ganze Körperlänge [highlighted by the the dorsal surface of the gut, this organ first keeps the author], ist unverästelt, vorn merklich weiter als hinten, shape of a fairly narrow slit with thin walls in the area of in der Mitte etwa so breit als der Nervenstrang, und seine displaced tubules in the lateral part. Thereafter, it appears Wandung ziemlich consistent, an den Enden aber so zart, as a wide sac compressed between the walls of the trunk dass ich sie hier nicht von den anliegenden Muskeln and the septum separating it from the main body cavity abprepariren konnte.” [Translation from German: “about (cf. Plate XII, Figs 14 and 15 gl [“gl” is an abbreviation used whose significance I cannot be clear; I want to call it the side in the figures]). Concerning the walls of this sac, these are channel. It runs through the entire body length, is unbranched, quite delicate. Their thin external membrane is internally anteriorly markedly wider than posteriorly, in the middle about lined by a delicate cylindrical epithelium. The internal as wide as the nerve cord and its walls are fairly consistent but cavity of these sacs is everywhere empty, except for the at the ends so delicate that I could not dissect them from the anterior and posterior ends where little amounts of fine- adjacent muscles.”] Grube describes further a thin septum, grained substance resembling flakes were found (might by which this canal is separated from the nerve cord. this be due to the long preservation in ethanol?). The septum between the lateral channel and the nerve cord, As to the specimen of P. capensis investigated by me, in which was described by Grube and in which he illustrated the entire description of Grube holds true only that this openings detected by him, is not a peculiar formation structure, called by Grube the side vessel, lies together with but a neurilemma enclosing the nerve cord and often the nerve cord in a specific part segregated from the main separated at considerable distance from the cord. The

Australian N Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” openings in it correspond to areas where nerves emanate. developed, according to the strong musculature, the Apart from the neurilemma I clearly did not observe any raptorial jaws, strong armature completely covering the other septum in any of the sections. body surface, the ability to produce live young, which generally require considerable energy of life. Determining the role of the described lateral sacs [salivary glands] in Peripatus is a difficult task. The more I find Hence, similar to the presumed dual role of segmental it difficult to propose anything reasonable regarding organs [nephridia] that open via the legs of the trunk, it their significance, as I did not have the possibility seems possible that one part of the corresponding organs to verify the finding in the investigated specimen by of the anterior pair [slime papillae], which have received

analysing additional specimens and I could not clarify predominant development compared to the others, has Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 the relationship of these to the other organs based on formed a large branched excretory organ extending longitudinal sections, in particular in order to clarify, throughout the entire body [Sänger probably means the whether these sacs indeed open externally via the first pair slime gland in this place]; the other part, representing a of legs [slime papillae] together with the above-described simple tube with thin walls, has become a respiratory or muscular glandules [slime glands]; and also whether gas storage organ [Sänger probably means the salivary gland there is a connection between them and the segmental at this point]. Recalling the circumstances, under which glandules of the individual segments, although this seems Lacordaire found P. Edwardsii, although these contradict unlikely to me. the reports of the remaining travellers, one considers that the worm seeks its prey not only on land but pursues it However, the difference between the description of Grube sometimes also in water. [M. Lacordaire is mentioned by and what I observed in P. capensis appears to me fairly both Audouin and Milne-Edwards 1833 and Blanchard 1847. strange. The extent of these organs is so considerable He found the initial specimens of Epiperipatus edwardsii in that it is difficult to assume a mistake in the statement Cayenne, French Guiana, that were studied by Audouin and of Grube: “in der Mitte etwa so breit als der Nervenstrang”. Milne-Edwards 1833.] Then the existence of a specific [Translation from German: “in the middle about as wide gas reservoir [i.e., the salivary gland] in the worm’s body as the nerve cord”.] Could not this discrepancy in size receives more importance. Not without reason Peripatus measurements be explained by the ability of the tube was almost placed among the diplopods — a connection to expand in some cases to the size of a sack, as in our between them does exist, as between animals of the same example? Could not this environment and equal life conditions. It is therefore very reasonable to propose elements in the organisation of Page 250 Peripatus as precursors for the organisation of articulated circumstance, if confirmed, serve as an indication that animals [Sänger probably means arthropods here]. As the these thin-walled organs function as gas reservoirs? Would segmental organs [nephridia] of the trunk segments it be possible to consider, similar to the segmental might serve as the prototype for tracheae; in the same organs [nephridia] of the trunk segments whose glandular manner, part of the segmental organ of the mouth segment tube is accompanied by membranous airborne accessory [highlighted by the author; Sänger obviously means the slime tubules, that the branched gland of the first segment papilla segment], which carries the most anterior pair of is also accompanied by organs homologous with these legs [slime papillae], might be the initial form of internal tubules, except that they represent incomparably large reservoirs for the air, if this part in fact plays its attributed development and large size? role. [Note that Sänger was unable to detect the genuine tracheae, as his specimens were preserved in ethanol, in which I have already mentioned that neither Milne Edwards these structures become invisible. The tracheal system of velvet nor Grube describe specific respiratory organs in worms was discovered a few years later by Moseley (1874).] Peripatus. Grube included the following statement about the respiration in a footnote at the end of his study: Page 251 “Die Athmung geschieht villeicht in ähnlicher Weise, I offer herein these analogies and conclusions as wie bei den Hirudineen.” [Translation from German: conjectures, but I believe that they are not devoid of “The respiration occurs perhaps in a similar way as in the likelihood. hirudineans.”] However, previous researchers doubtlessly neglected the peculiar lifestyle of Peripatus. Apart from segmental organs, it was possible for me to follow in detail the organisation of the nervous system of The majority of worms live in water, Oligochaeta live Peripatus, which exhibits some interesting peculiarities. in humid earth; Peripatus, however, is the only terrestrial animal [highlighted by the author] in the entire division of In the first anterior segment, there are two massive cephalic worms that is an airborne worm. While in other worms, ganglia [i.e., the brain] occupying nearly the entire dorsal the humid surface of the skin or specific external simple or half of the cavity of this segment. Both ganglia are branched appendages can serve for breathing, in this case separated anteriorly and posteriorly from each other by a similar conditions would be insufficient. Peripatus must vertical muscular septum extending from the walls, but have internal respiratory organs and besides sufficiently in the median part they fuse with each other and form a

Australian 2021 Zoologist O Tait et al. unitary, transverse nerve mass, the internal fibres of which cup including a large number of nerve cells and containing cross from one half to the other. Both interconnected pigment inside, which is similarly deepened in the middle. ganglia are covered with a distinct layer, the neurilemma, In this depression, a spherical lens is situated. Above the which in several places is separated from the neural lens, which is stained yellow in my preparations, the cornea matter. In the organisation of the ganglia, it is possible to forms a closed vault. In areas where the cornea faces distinctly recognise the outer neural matter consisting of the exterior, it is transparent, whereas it is lined with an numerous small cells and the inner, finely fibrous matter abundant mass of pigment on the sides. Hence, a distinct (Leydig’s Fibrilläre Punktsubstanz). Under the medium pupil exists here. The eye possesses its own muscles for magnifications, the fibrous nervous matter appears as movement. [Note that there are in fact no such muscles and

a nearly formless mass, due to the extraordinarily fine that the onychophoran eye is rather immovable (Beckmann et Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 fibres. However, upon closer inspection, even of transverse al. 2015; Kirwan et al. 2018; Mayer 2007).] sections, it is possible to clearly follow fibres extending to the periphery usually from the median parts of the Each antenna, lying in front of the eyes, receives a thick fibrous matter; especially in the cephalic ganglia, due to nerve from the anterior bulge of the cephalic ganglia. In their considerable volume. It is possible to clearly follow the mouth segment and behind the mouth cavity, the bundles of fibres along their considerable extent towards cephalic ganglia give rise to two nerve cords, one on each the nerves emanating from the ganglia. Each fibre does side, closely adjacent to the muscular walls of the pharynx. not exceed 0.002’’’ in width. [Note that triple prime, as used A ring actually does not exist here, since these nerve cords in watchmaking, represents a ligne (~2.26 mm). This suggests form curved arcs after passing ventrally on each side of that Sänger’s value 0.002’’’ corresponds to 4.52 µm]. These the pharynx. They then run along the trunk, remaining fibres are also seen within the nerves and they are always at a considerable distance from each other. Whereupon, mingled with individually scattered nerve cells [evidence the further away from the beginning, the more they move for medullary, cord-like organisation of nerves!]. On the side away from each other. They show a nearly lateral position of the brain directed toward the muscular mouth cavity, a in the middle of the ventral part of the trunk. The width peculiar bulge of spherical shape [hypocerebral organ] is seen of each cord differs somewhat along its length. The bends on the surface of each ganglion, the substance of which also linking them to the cephalic ganglia are fairly thin and consists of nerve cells and only in the centre of this bulge a thereafter, the cords initially exhibit a somewhat ovoid light area is seen. Grube regarded this structure as the organ shape. Further in the anterior part of the body, they are of hearing of Peripatus, describing it as a vesicle filled with flat, but widen soon, after which they take up a roundish- fluid that contained an otolith [sic!]. My preparations (Plate ovoid or oval shape. Toward the posterior end, they XII, Fig. 9 ac [“ac” is an abbreviation used in the figure]) make flatten again, but become nearly roundish near their end such an explanation impossible. In my view, these bulges where they pass from the ventral side to the centre of the should be considered as accessory ganglia. It might well be body cavity. Hence, Grube states quite imprecisely that that they give rise to nerves toward the mouth cavity, to the they represent flat bands. Throughout the entire length, tactile papillae [oral lips] surrounding the mouth opening. both cords are linked with each other via commissures, In any case these are not hearing vesicles. Rather, I would especially evident in the anterior part. Here, due to the regard another distinct vesicle as the organ of hearing, close proximity of the cords, the commissures are short which is very small compared to these neural bumps. They and rather strong. The first anterior commissure can be do not lie on the side directed toward the mouth cavity but regarded as the part closing the neural circumoral ring. near the opposite dorsal surface of each brain hemisphere In the remaining segments, the commissures are very among the nerve cells somewhat further posteriorly, in the thin, long and apparently pass between the two layers of region where the cephalic ganglia continue into the nerve longitudinal muscles in the middle of the ventral side. cords passing around the pharynx to the ventral side. In Throughout their entire length, the cords are separated this small oval-shaped vesicle [giant neuron?], a transparent from the remaining body cavity by a septum mentioned cavity and a very sharp corpuscle, like a core inside, are above and their commissures pass through this septum. In seen. [Note that a giant neuron has been detected in the same some sections, specifically in the anterior segments, it was position in each brain hemisphere by Schürmann (1987).] This clearly seen that the commissures form a small ganglionic thickening [most likely an artefact or misinterpretation] with Page 252 comparatively large oval cells directly at the septum. In vesicle is easily recognisable among the nerve cells, as it is each segment, a prominent nerve emanates from the considerably larger. The diameter of the nerve cells ranges between 0.004’’’ and 0.006’’’ [i.e., between 9.04 µm and Page 253 13.56 µm], whereas this vesicle measures 0.026’’’ in length nerve cord into the leg, which transforms into three and 0.021’’’ in width [i.e., 58.76 µm in length and 47.46 µm branches after entering the leg cavity, as well as nerves to in width]; the identified internal nucleus measures 0.0003’’’ the muscles of the body wall. The existence of branching [i.e., 0.678 µm]. The eyes are connected to the cephalic nerves has been unknown thus far. At the posterior end, ganglia and located on the dorsal side at the basis of the nerve cords exhibit a peculiar feature in that they antennae. The optic nerve arises from the fibrous median leave space for the outgoing tracts of the female genital matter of the cephalic ganglion. It forms some sort of neural organs and deviate from their course. Each cord passes

Australian P Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” on the ventral side to the middle of the body cavity, finds a complete correspondence between these fibres abruptly bending directly in front of the connection of and neural dark-rimmed fibres of vertebrates and even the two lateral genital tubes to the common outgoing points out that at first sight these fibres appear somewhat genital duct, and thereafter transforms into branches as hollow vessels. So, he says on p. 170 (l. c.): “Ich selber without joining the cord of the other side [this is most habe die letztern früher für Blutgefässe ausgegeben, denn likely incorrect; see Mayer (2016)]. was ich in meinen Mittheilungen über das Nervensystem der Anneliden (Archiv für Anat. and Phys. 1862) als Similar to the cephalic ganglia [i.e., the brain] that are Längsblutgefäss des Bauchmarkes bezeichnet, ist eine equipped with a sheath, the nerve cords are also covered solche ‘Faser’. Die Aehnlichkeit zwischen einen [correct

throughout their entire length with a distinct membrane spelling: einem] leeren Blutgefäss und diesen Nervenfasern Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 [neurilemma], everywhere exhibiting a double outline. ist aber auch, was ich jetzt noch sehe, in der That gross.” Apparently, also the nerves emanating from the cords retain [Translation from German: “I myself considered the latter as this sheath. In the region of cords that face the ventral side, blood vessels, since what I regarded as a longitudinal vessel there are utterly the same cells that also comprise the of the ventral nerve cord in my Communications about peripheral matter of cephalic ganglia. The fibrous mass the Nervous System of Annelids (Archiv für Anat. and (fibrilläre Punktsubstanz) is directed internally and exhibits Phys. 1862) is such a ‘fibre’. From what I still see, there is in its size a larger development than the cellular matter. indeed high similarity between an empty blood vessel and Inside the fibre mass of the median part of the nerve cord, these nerve fibres.”] Despite such an apparently close near the border to the nerve cells, clearly delineated oval analogy, I definitely could not recognise, even at high holes of different sizes [most likely giant fibres] are noticeable magnifications, any dark rim in the holes described by in subsequent sections ranging from 0.01’’’ to 0.02’’’ [i.e., me and I saw neither a covering layer, which according from 22.6 µm to 45.2 µm] in their longest diameter. The to Leydig represents a distinct layering, nor an internal position of these holes remains the same in all sections axial substance, so that I must stay with the assumption and given their different size, the correspondence of these that I am still dealing with internal hollow channels, quite holes is especially evident (Plate XII, Fig. 20, o [“o” is numerous and running along the nerve cord, closer to its an abbreviation used in the figure]). In order to clarify the ventral side14. significance of these holes, two suggestions can be made: either several thick fibres of different size should be assumed To summarise what has been said about the nervous among the extremely thin nerve fibres [giant fibres of varying system of P. capensis, I consider it as necessary to add a diameters have been demonstrated later, e.g., by Schürmann few words with regard to the fact that I was unable to find & Sandeman (1976)], or one could assume that hollow that arcuate connection at the posterior end of the ventral channels are passing here. In the first case, the impact cords, which Grube saw in P. Edwardsii and which he of carmine should have stained these formations and describes as a distinct loop. Contrary to this, I observed, accordingly they would not appear as colourless transparent in cross sections through the posterior end of the body, a holes in sections [giant fibres typically do appear colourless distinct branching [sic] of each cord, which in histological sections; see, e.g., Mayer & Harzsch (2007)]. Hence, due to the appearance of preparations and the Page 255 persisting uniformity in the arrangement of holes, the only is located here in the middle of the body cavity on likely conclusion would be that apparently the holes seen in each side of the rectum rather than on the ventral sections represent sections through channels running inside side of the body. This difference in a major anatomical the nerve cords [Sänger’s “channels” are most likely giant feature appeared strange to me, but, to avoid oversight fibres]. Klapared’s known observation of thick median fibres on my part, I was trying to find some explanation in some Oligochaeta, which he initially found in Pachydrilus, for such a contradiction. As a possible explanation, Clitellio and a few other small forms of these worms and I believe it might be due to the difference in the which he compared to the thick fibres of crayfish and some 14 The investigations of Klapared — Histologische Untersuchungen über insects, might speak in favour of the first suggestion, i.e., den Regenwurm (Zeitschrift f. wissens. Zool. XIX. II. 4. 1869.) — having the assumption of internal thick fibres. Leydig13 confirmed appeared at the end of the last year and consequently considerably later than the second congress, convinced me even more that between this discovery and found three giant dark-red fibres (riesige the channels found in Peripatus and the above-mentioned thick nerve dunkelrandige Nervenfasern) [the correct translation from fibres of Klapered [sic] and Leydig in Oligochaeta have only little in German would be “dark-rimmed”, rather than “dark-red” nerve common. In Klapared’s drawings of cross sections (Plate XLVII, Figs 3 and 4, e. f.) as well as the description (pp. 588 and 589), it is stated that fibres], as compared to the other these formations do not lie in the middle of the nerve cord, as Klapared previously thought, and not in its dorsal part, as stated by Leydig, but Page 254 rather outside the neural substance, in the internal neurilemma lining the neural substance. Klapared illustrates these tubes with thick layered nerve fibres, in Lumbricus agricola, which run along the walls, with their varying size throughout, and expresses doubt about nerve cords in their dorsal part. In a detailed description their assigned role as simple nerve fibres of giant size. With regard of these fibres, Leydig speaks about the axial fluid and to the oval holes detected and illustrated in sections of nerve cords of Peripatus by me, in contrast, these lie inside the neural matter and marrow or fat layer, which comprises the outer lining specifically in its fibrous part close to the border of nerve cells but far of these fibres due to the lack of Schwann’s sheath. He away from the external rim of the cord [i.e., in a median position]; and, as I already said, they do not possess any own sheath. 13 Leydig. Vom Bau des thierischen Körpers. S. 154 and 170.

Australian 2021 Zoologist Q Tait et al. position of the external genital opening. In P. capensis belonging to the body of articulated animals [arthropods investigated by me, this opening is totally shifted toward are probably meant], apparently insects, but also quite the posterior end, whereas in P. Edwardsii it lies far away numerous plant particles. Based on this, the assumption from the end between the penultimate pair of legs. of Grube is not justified that Peripatus feeds on blood of Perhaps the topographical conditions of the internal other animals — it is apparently an omnivorous animal cavity in the posterior part of the body of P. Edwardsii or, more precisely, judging by the integument, claws and enable the prominent development of the commissure jaws — predominantly predacious. or the formation of an arc, but in P. capensis the uterus, consisting of two lateral tubes, occupies together with In the posterior part of the trunk in the specimen of P. th th the rectum the entire posterior end of the body and, as capensis investigated by me, between the 16 and 17 Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 has been mentioned already, even displaces the nerve pairs of legs, I noticed in the subcutaneous muscles on cords to the middle of the cavity, without leaving any one side a dark elongated body of considerable size, space for the formation of the loop. having the appearance of a foreign accidental formation. A closer inspection revealed that this body is a parasite Regarding the circulatory system, it must be noted that [apparently the first record of an acanthocephalan!] enclosed there is only one dorsal vessel [i.e., the heart]; the two in an almost opaque sheath. I did not succeed in dissecting lateral vessels mentioned by Grube [i.e., the salivary this parasite as a whole, but after having destroyed the glands], as we have seen, have nothing to do with the sheath I could convince myself that the major part, if not circulatory system. The dorsal vessel does not show the the entire surface, of the enclosed parasite was covered same size along its entire length. It becomes considerably with transparent hooks resembling the hooks on the wider posteriorly. It begins as a transverse slit behind the introvert of Echinorhynchus. Since the body of the parasite cephalic neural ganglia and ends similarly as a slit, albeit was damaged during the extraction, I was unable to wider, opening into the posterior part of the body cavity. investigate it more closely. The vessel lies in a furrow formed by the longitudinal muscles and on the ventral side, especially on its sides, is In conclusion of my notes about the organisation of P. additionally surrounded by a peculiar loose cellular tissue capensis, I have the chance to describe an additional new [most likely pericardial cells], which Grube compared to the species of this worm. A student of Professor Leuckart, fat body of insects. With respect to the other organs in the Mr. Pessler, found this species [Euperipatoides leuckartii body of Peripatus, small subcutaneous glandules [most likely (Sänger, 1871)] in New Holland [now called Australia], ventral/preventral organs] deserve attention, which Grube northwest of Sydney. So far, no other species has been did not notice. These subcutaneous glandules, if they can known from New Holland and the one obtained from be at all named as such, are arranged along the ventral there shows some quite considerable differences. midline. I already mentioned in the description of external features the dark dots situated in the middle of each leg This Peripatus possesses fifteen pairs of legs; the first pair pair. While describing living P. capensis, Frauenfeld noted a without claws and 14 pairs with claws [sic!]. It shares this black discontinuous line running along the middle of the feature with P. brevis described by Blanchard and found at ventral side. This line, most likely, is associated with the the Cape of Good Hope, but the sizes of the worms of these glandules noticed by me. Exactly in the middle between two species are very different; while P. brevis measures 43 each pair of legs, directly between muscles and skin, is mm in length, the specimen from New Holland is exactly located a fairly translucent vesicle seemingly filled with half this size, equalling only 21 mm. [See comments about cells. I was unable to find out, whether this vesicle has an “P. brevis” on page 240 of the translation above.] The genital external opening, but in the entire place where it occurs opening lies in the middle of the ultimate pair of legs the integument forms a depression closely corresponding and it is this feature in that it differs from P. Edwardsii to it. In front and behind the vesicle, between muscles and and P. capensis. The anus is situated at the posterior tip skin, at some extent a small longitudinal space [apodeme?] of the body, but is directed considerably downward, to is noticeable, disappearing in the interspace between the the ventral side, and is comparatively large, surrounded legs. I leave it open as to which role these vesicles play. I by a soft ridge of the skin, which I have not noticed in can only state that the neural commissure sometimes runs P. capensis. The colour of the worm is very dark, almost fairly close to the vesicle. black on the dorsal side, but the ventral side is lighter and greyish in colour. The papillae occur on the dorsal With respect to the organisation of the digestive tract and and the ventral surfaces, but on the ventral side they are female genital organs, as well as the muscular system of the more elongated in transverse direction. In the middle of worm, Grube has given in his study a fairly comprehensive each pair of legs, an oval bright spot is conspicuous, which is not covered with papillae. (This spot corresponds to Page 256 the dark depressions of P. capensis, under which there are and correct understanding and hence, I will not elaborate situated glandules [ventral/preventral organs] described by on them. I only mention that in the lumen of the gut me.) As in P. capensis, there are large red and black small in the specimen investigated by me I came across a papillae, however, the red papillae are considerably fewer considerable amount of individual parts, undoubtedly in number than the black ones. A line extends along

Australian R Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.”

Page 257 system of the group Onychophora, of which Peripatus is the dorsal midline, consisting only of black papillae, but the only representative. At the beginning of the article, I this line is comparatively weakly developed. The dorsal already spoke about different existing scientific views and papillae are arranged in quite regular transverse rows mentioned that at the time when the French researchers [plicae] and each row is segregated by a fairly deep furrow excluded this group at all from the division of worms, most from the subsequent row. The skin between the papillae is German systematists allocate for it a position as a distinct of dark-grey colour; on the legs, the papillae are arranged order in the class of ringed worms. The impression that I quite sparsely to each other. received from the investigation

The legs possess soles, as in P. capensis consisting of three Page 258 Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 pads, but the shape of the pads is here considerably of P. capensis, has convinced me that Peripatus, being different (Plate XIII, Fig. 33): the upper pad is black, undoubtedly a worm, represents just as sure a peculiar strongly arcuate and considerably narrower than the transitional form from worms to articulated animals other two. The second and third pads are of yellow-red [arthropods are probably meant]. colour, much shorter than the first one, but wider. The clawed segment [foot] of the leg is differentiated by its The existence of segmental organs in the body of Peripatus, quadrangular shape because on each side of its tip there distinct external segmentation, expressed in various is a papilla [one anterior, one posterior and one median] (in numbers of paired legs and the type of organisation P. capensis there are three papillae [two anterior and one of the nervous system (representing considerable posterior; note that this arrangement is incorrectly stated in the correspondences to the nervous system of Hirudinea, text, as one anterior two posterior]). The claws are smaller Oligochaeta and Appendiculata polychaeta, such as than in P. capensis. Sabella, Serpula and others) prove the affiliation of this animal to the worms. The organisation of the mouth is fully the same as in the other species, except that the soft parts surrounding the The developmental degree of the nervous system is in mouth and the genital opening are of white rather than many respects inferior to the developmental perfection of yellow colour, as in the others. However, the colour might this system in many other worms. The ventral cords do have been affected by ethanol, in which the worm has not represent ganglionic thickenings, the nerve cells and been preserved. fibrous matter are distributed in them evenly along their entire length, the cords are widely spread apart toward In addition to this description of external features of the the body walls. The circulatory system is developed very worm, I can provide the main dimensions of the described weakly and is represented by the singular dorsal vessel, specimen. open at both ends.

Body length — 21 mm, body width (largest) — 3.03 Similar deviations, natural within the type of worms, mm. Length of antennae ranging from 1.6 to 1.73 mm, considerably move away Peripatus from articulated animals width at the basis of antennae — 0.389 mm, their width [arthropods are probably meant]. in the middle — 0.26 mm, length of mouth opening including soft surrounding parts — 0.952 mm, upper On the contrary, other details bring the Onychophora length of legs — 2.16 mm, width at the basis — 0.86 closer to this more advanced type. The main reason for mm (not everywhere the same), length of claw segment this rapprochement lies apparently in the terrestrial and — 0.26 mm, diameter of genital opening including soft predatory lifestyle. Due to the terrestrial lifestyle of the surrounding parts — 0.65 mm, diameter of eye — 0.11 worm, we can assume an adaptation of segmental organs mm, diameter of papillae covering the skin ranging from to the process of respiration as well as to recognise the 0.04 to 0.08 mm, length of claw — 0.15 mm, width at lateral sacks [salivary glands] as gas reservoirs (?) [question claw basis — 0.105 mm. This species is described based on mark by the author]; the predatory tools are expressed a specimen belonging to Professor Leuckart and, upon his in the prominent claws, the sharp jaws, the general agreement, I suggest to name it Peripatus Leuckartii. armament of the body surface, the strong development of the secretory glands producing the slime etc. The short diagnosis of it can be expressed in the following words: Species with 15 pairs of legs; genital opening All these correspondences, in my view, justify the between legs of last pair. Legs equipped with three sole establishment of Onychophora as a distinct class in the pads [spinous pads] — a long arcuate one and two short division of worms, equally independent from ringed straight ones. Found in New Holland [i.e., Australia]. worms as the classes Gephyrea [Echiura, Sipuncula and Priapulida], Enteropneusti, Rotatoria and others. This After having learnt about the organisation and peculiarities weight and significance was precisely assigned to the group of Peripatus, it remains for us to summarise some results Onychophora in the very recent time by Gegenbaur15, who of systematic interest and, if possible, to answer the states in the last edition of his Comparative Anatomy: “Auf question about the position, which it occupies in the 15 Grundzüge der vergleichenden Anatomie. Zw. Aufl. 1870. S. 159.

Australian 2021 Zoologist S Tait et al. gleiche Stufe mit Gephyreen und Räderthieren muss ich Fig. 7. Armed papilla from the surface of the trunk: a — die Onychophoren stellen… Sie scheinen noch früher als apical needle [sensory bristle]; b — spines or leaves [scales] die vorhergehenden (Gephyreen) von einer den Würmern covering the papilla; c — attachment points of such zu Grunde liegenden Urform sich abgezweigt zu haben, spines, subcuticular cells. und weisen in ihrer Organisation auf eine gemeinsame Abstammung mit gegliederten Organismen, welche in Fig. 8. Part of transverse section through the cephalic part höhere Zustände, wie wir sie bei den Arthropoden finden, of the body traversing the eye: gn — left neural ganglion übergegangen sind.” [Translation from German: “I have to cut in its anterior part; t — sheath surrounding it; n — give the onychophorans the same rank as geophyreans and neural matter, bowl surrounding the bottom of the eye

rotifers… They seem to have diverged even earlier than the and connected to the ganglion; p — pigmented body of Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 aforementioned (gephyreans) from a basic prototype of worms the eye; l — lens; c — cornea, transparent in the anterior and indicate in their organisation a common ancestry with part; m — transverse muscles; ml — longitudinal muscles; articulated organisms, which have acquired more advanced a — papillae equipped with needles [sensory bristles]; b — states, as we find in arthropods.”] In another place, Gegenbaur blunt papillae from head surface. (p. 162) expresses the thought, which correctly reflects the natural relationships and makes the more intelligible the Page 260 connection of Onychophora to animals with articulated Fig. 9. Cross section of cephalic ganglia made further limbs [i.e., arthropods]: “the relationship of Arthropoda to posteriorly through the region where both ganglia unite Annelida”, he says, “seems to be into a unitary body and where the anterior muscular septum separating them has disappeared; nc — strip of Page 259 neural matter in the upper part of the brain consisting of very close and consequently the arthropods should be fibres crossing from one ganglion into the other; nb — united with the worms into one [highlighted by the author] fibrous matter; na — peripheral matter of the ganglia; ac division. However, apart from practical considerations, — neural accessory bumps [hypocerebral organs] pointing I was prompted to still treat them separately by the toward the mouth cavity and regarded as hearing vesicles; circumstance that mollusks as well as echinoderms exhibit t — sheath [neurilemma]. close relationships in the noted groups and an affiliation to worms. Therefore, I regard the division of worms as Fig. 10. Section through the mouth opening in the region a group of the animal kingdom, which reveals changes where the large jaws are situated; gn — cephalic ganglia; in the type in many directions that represents in their t — their sheath; oe — mouth cavity that opens ventrally; most advanced forms via the ringed worms a direct mx — jaws; l — lips; p — section of the first (false) pair of transformation to the articulated and echinoderm animals legs [slime papillae]; lp — cavity of the leg. [i.e., representatives of Articulata and Echinodermata].” Fig. 11. Keeled protrusion [tongue] in the upper part of the mouth cavity above the jaws: q — papillae [this Explanation to Illustrations label is apparently missing in the figure]; c — cuticle; sc — Plate XII. subcuticle; m — muscles. Fig. 1. Peripatus capensis Gr. A — from bottom side, B — Fig. 12. Section from the posterior part of the mouth in from upper, dorsal side. region where the cephalic ganglia connect to the ventral nerve cords. The letters have the same meaning as in Fig. 2. Anterior part of the body from below to illustrate the previous illustrations: e — tube opening in the first mouth opening with surrounding lips (l.); mx — large (false) leg [slime papillae], internally lined with a delicate posterior jaws; mx’ — thin anterior jaws; p — keeled cylindrical epithelium. protrusion [tongue] with papillae. Fig. 13. Surface of the lips surrounding the mouth opening: Fig. 3. Leg represented from below; pl — narrow sole q — papillae [mislabelled with “g”]; l — underlying cell platforms [spinous pads]; o — opening of segmental bodies. glandule. Fig. 14. [The labelling is completely missing in this figure; Fig. 4. Posterior body end of one of the three specimens of A and B seem to have been mixed up.] A. Part of section P. capensis; x — claws, one on each side. behind the mouth opening; oe — oesophagus; n — nerve cords connected by a commissure; i — blind anterior end Fig. 5. Apical part of the leg at high magnification: pl — of the digestive tract with a prominent epithelial layer; gs sole platforms [spinous pads]; v — oval vesicular elevation — tubes with muscular walls that were considered as the on bottom side of the claw pyramid; d — openings of male genital organs. B. Subsequent section illustrating the these elevations [probably areas where the bristles broke off]. digestive tract (i) quite at the wide beginning.

Fig. 6. Separate claw of the leg. Fig. 15. Section through the anterior part of the trunk;

Australian T Zoologist 2021 Translation of Sänger’s (1871) “Peripatus capensis Gr. and Peripatus leuckartii n. sp.” gl — organ described by Grube as the lateral channel Fig. 24. Same section through its different part, to or vessel [salivary gland]; a — dorsal blood vessel; m — illustrate the end of the tube gl [secretory duct] and section of longitudinal muscular masses. numerous branches of the tubules gs [most likely the endpieces] considered as male genital organs [slime glands]; Fig. 16. Organisation of the walls of the glandules [salivary a — dorsal blood vessel. glands] described as the male genital organs. (gs — in sections) ml — longitudinal muscles; mt — transverse Fig. 25. Section from the posterior half of the trunk: n muscles; s — glandular cells. — nerve cord; nv — section of the outgoing leg nerve; so — sections of the segmental organ passing into the

Fig. 17. Section of branched segmental organs situated leg cavity; i — intestinal tract; a — blood vessel; ov — Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/doi/10.7882/AZ.2021.022/2879036/10.7882_az.2021.022.pdf by guest on 26 September 2021 between each two pairs of legs, a — median glandular uterus; x — ovary (?). tube; b, b’ and b’’ — thin-walled tubes surrounding it. Fig. 26. Section near the posterior end of the body through Fig. 18. Same section, but cut through the part of organs the rectum (i) in the region where the uteri (ov) still lie directed anteriorly in the region where the thin-walled separately on each side of the body and where the blood tubes are further developed. vessel (a) is still sectioned. The nerve cords pass here from the ventral to the dorsal side; m — septum attached to Fig. 19. Schematised drawing illustrating in profile the the walls of the gut. position of the nervous system in the anterior part of the body; g — cephalic ganglion; oc — eye; ac — neural Fig. 27. Section through the region where the uteri unite in an arcuate fashion into a common outgoing tube on the Page 261 ventral side. The blood vessel has disappeared — a wide bump [hypocerebral organ]; n — ventral nerve cord; ph cavity has remained instead and is separated by a septum — mouth cavity with the keeled protrusion [tongue]; oe (m); n — endings of the nerve cords. — oesophagus [pharynx]. Page 262 Fig. 20. [The labelling is completely missing in this figure.] Section Fig. 28. Section of the posterior end of the body passing of the ventral nerve cord with outgoing commissure: ps — through the genital opening (vl); au — end of the rectum. fibrous matter; o — internal hollow channels [most likely giant fibres]; n — peripheral matter with cells; t — sheath Fig. 29. External view of the posterior end of P. capensis: [neurilemma]; g — ganglion associated with commissure vl — genital opening; au — anus. [this structure but might be in fact the entrance point of tracheal tubes]; m — muscular septum. Fig. 30. Peripatus Leuckartii n. sp. Head part of the body: an — antennae; oc — eyes; o — mouth surrounded by lips; Plate XIII. p1 — first (false) pair of legs [slime papillae]; p2 — second Fig. 21. Part of section through attachment point of leg to pair of legs [in fact the first pair of legs]. the trunk illustrating parts of branched segmental organs that lie in the interspaces between each two pairs of legs Fig. 31. Posterior end of P. Leuckartii: vl — genital opening; and extend into the cavity of the leg: so — glandular au — anus; gm — naked spot [ventral/preventral organs] central tube; sot — thin-walled tubes surrounding noticeable between each pair of legs along the midline. it; n — nerve cord; gl — tube with epithelial lining [salivary gland] (Settenkanal-Grube) [correct spelling: Fig. 32. Leg of P. Leuckartii from the upper side. “Seitenkanal” meaning “lateral channel”] running along the body side; ml and mt — muscles. Fig. 33. Leg from the bottom: pl — two sole platforms [spinous pads] of yellow colour; pn — sole arc [spinous pad] Fig. 22. Same section through the region where a nerve of dark colour. (nv) passes from the nerve cord into the leg: so — section of the above-mentioned branched organ [nephridial organ]; Fig. 34. Tip of the leg of the second pair, at whose claws a st — opening at the leg base [nephropore]. lump of slime has been preserved.

Fig. 23. Section through the attachment point of the Fig. 35. Tip of the leg in a cross section showing that it tenth pair of legs; gl and gl’ — ending of the tube labelled consists of 4 papillae arranged in a cruciform fashion. by the same letters as in the preceding illustrations; sot — branches of the segmental organ; so — outgoing [End of translation.] canal of the same organ leading into an opening situated at the leg base.

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Acknowledgements We are grateful to Irina Polyanskaya (Director of the of Sänger’s grave. We also would like to thank the two Library of the Polytechnic Museum in Moscow) for peer reviewers for their very constructive comments providing digital copies of the portraits of Sänger and on scientific accuracy and comprehension of the text. the corresponding references. We thank the staff of the The Conselho Nacional de Desenvolvimento Científico Moscow City Municipal Funeral Service and the State e Tecnológico (CNPq Brazil) is acknowledged for the Budgetary Institution “Ritual” for providing photographs support to ISO (290029/2010-4).

References

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