CXIX.-ASCIDIANS FROM MOZAMBIQUE, EAST AFRICA.

By R. H. MILLAR, Marine Station, Millport.

lNTRODUCTION. A small collection of littoral ascidians (class Ascidiacea; sub-phylum Tunicatal bas been made from various places on the coast of Mozambique, East Africa, by Mrs. M. Kalk of the Zoology Department, the University ofWitwatersrand, and the present paper gives an account ofthe collection. Most of the specimens come from the shores of Inhaca Island (lat. 26° S.) which lies at the mouthof Delagoa Bay and is almost due east of Lourenço Marques. There are also a few specimens from the shores of Mozambique Island (lat. 15° S.) and Santa Carolina (lat. 22° S.). The ascidians of East Africa have already been described by Michaeisen (1918, 1919, 1920, 1921) who summarized previous information and also added new accounts of his own. Systematic list of species. Family Polyclinidae Milne Edwards. Aplidium altarium (Sluiter). A. petrense Michaelsen. A. lubricum (Sluiter). Polyclinum macrophyUum Michaelsen. Family Polycitoridae Michaelsen. Eud·istoma 1·hodopyge (Sluiter). E. mobiusi (Hartmeyer). E. caeruleum (Sluiter). E. paesslerioides Micha.elsen. Clavelina enormis Herdman. Family Didemnidae Verrill. Diplosoma modestum Michaelsen. Didemnopsis sansibaricum Michaelsen. ?Didemmtm psammatodes (Sluiter). Family Ascidiidae Herdman. Ascidia incrassata Heller. A. arenosa Hartmeyer. Family Botryllidae Verrill. Botryllus plan'U8 (Va.n Name). Family Styelidae Sluiter. Symplegma viride Herdman. Styela marquesana Michaelsen. Polyandrocarpa tincta (Van Name). P. inhacae sp. n. A.M.N.H. ser. 12, vol. ix, 58 914 R. H. Millar on Ascidians from Mozambique

Family Pyuridae Hartmeyer. Pyura sansibarica Michaelsen. Herdmania momus (Savigny).

DESCRIPTION OF SPECIES. Family Polyclinidae Milne Edwards, 1842. Genus Aplidium Savigny, 1816. Aplidium altarium (Sluiter), Fig. I. Amaroucium altarium Sluiter, 1909, p. 105, pl. 5, fig. 9. Aplidium altarium Michaeisen 1919, p. 90. Known Distribution.-South of Ceram, Indonesia ; Zanzibar. Locality.-Mozambique Island ; three colonies. Description.-The colonies are no more than 4 rnm. thick, and the largest one is 1·8 b~I·O"ém. across. After preservation in alcohol the colour is pale pink-grey with lighter spots marking the zooids. There is no obvious arr~ement of the zooids in systems and no cornmon cloaca! openinga are vi~ible to the naked eye. The surface is smooth and the

Fig. I.

A

Aplidium altarium (Sluiter). A, zooid. B, larva. consistency of the colony soft. There is no foreign matter embedded in..Jlt the test or enerusting the surface. In structure the zooids agree closely-~ with Sluiter's and Michaeisan's descriptions. The large number ofJt folds on the stomach is especially characteristic of the species, Michaelsen~!~ having noted 43, and the present material showing 30, 36 and 40 in throoJ zooi"ds examine. d . •.• ··.~~ ~~" ~ A number of zooids were carrying embryos and Iarvm, generally from: ~: one to three in each breeding zooid. The larva me~ures about 0·6 mm1.i R. H. Millar on Ascidians from Mozambique 915 from the end of the papillre to the base of the tail. There are the three papillre as usual in the genus, and four rounded anterior ampullre or vesicles ·detached from the body of the larva. The sensory vesicle contains both ocellus and otolith. A plidium petrense Michaelsen. Aplidium petrense Michaeisen 1919, p. 92, figs. 5-7. K nown distribution.-Zanzibar ; Madagascar. Locality.-Mozambique Island; two colonies. Description.-The larger of the two colonies is 1·1 cm. by 0·5 cm. across and about 0·6 cm. tall. Both colonies are attached to small pieces of algae. The test is smooth, soft and semi-transparent with the zooids showing through. There is no foreign matter. Six pointed lobes surround the atrial opening. There are 24 folds on the stomach. Although my specimens have seven rows of stigmata compared with five found by Michaeisen I think there is little doubt that we are dealing with A. petrense.

A

Aplidium lubricum (Sluiter). A, zooid. B, la.iva.

Aplidium lubricum (Sluiter). Fig. 2. Amaroucium lubricum Sluiter 1897, p. :n. pl. 1, fig. 9, pl. 5, fig. 1. Michaeisen 1919, p. 100. Known distribution.-Durban, Natal. Locality.-Inhaca Island; one specimen. 58* 916 R. H. Millar on Ascidians from Mozambique

Description.-The colony is a sheet 5·5 cm. by 2·0 cm. across and 0•6' cm. thick. The test is semi-cartilaginous. The zooids seem to he,' arranged in linear systems but the grouping is not very distinct. Thé ; zooids may reach 4 mm. in length, of which the thorax occupies abou( 1·8 mm. There are eight or nine rows of stigmata. The stomach has · about 16 undivided longitudinal folds. Some of the zooids have larvlé intheatrial cavity. The larva is about 0·4 mm.long from the end ofthe: papilloo to the base of the tail. There are three anterior papilloo. Maily, small detached epidermal vesicles surround the anterior end of the trunk' and extend backwards along the doraal and ventral surfaces. Both ' otolith and ocellus are present. , The zooids of the colony from Inhaca Island agree well -with Sluiter's •-• original description, but the form of the colony and the shape of the} systems are a little different. I do not think that these differences anfJ as important as the ,:r~oints of resemblance, and consider that the identi"" fication is well estaJilished.

8

Polyclinum macrophyllum Michaelsen. A, thorax of a zooid. B, part of gut. C, larva. Genus Polyclinum Savigny, 1816. Polyclinum macrophyllum Michaelsen. Fig. 3. Polyelinwm macrophyUum Michael!en 1919, p. 82, figs. I, 2. Known distribution.-:-Madagascar; W. Australia. Locality.-Mozambique Island ; three colonies. Description.-Tbe colonies are flat,· up to about 4 mm. in ~u • ..,Al .• .,.,~.tii] and dull purple brown. There is little to add to Michaelsen's R. H. Millar on Ascidians from Mozambique 917 description of the zooids. In the present specimens the wall of the stomach bears a. number of small round ma.rks which give the stomach a. slightly areolated appearance but the marks are not raised. Michaeisen described the stomach as smooth-wa.lled. Two of the colonies contain larvre. These maasure a bout 0·4 mm. long from the end of the papillre to the base of the tail. There are, at the anterior end of the trunk, three papillre and four rounded a.mpullre. Both otolith and ocellus are present.

Fig. 4.

A

c

Eudistoma rhodapyge (Sluiter). A, small eolony. B, large eolony; C, larva.

Family Polycitoridae Michaelsen, 1904. Genus Eudistoma Caullery, 1909. Eudistoma rhodopyge (Sluiter). Fig. 4. Distoma rhodopyge Sluiter 1897, p. 12, pl. 1, fig. 2, pl. 3, figs. 5, 6. Polycitor (Eudistoma) rhodopyge Hartmeyer 1909, p. 1432; Michaelsen, 1919, p. 72. For synonymy see Michaelsen, 1934, p. 141. Known distribution.-Mozambique; Durban; False Bay and Still Bay, Cape Province. Localities.-Inb.aca Isla.nd ; Mozambique Island ; Santa Carolina. Desc1iption.-The collection contains saveral colonies which vary . from closely grouped short conical masses attached by their narrow ends, to taU finger-like inassas fairly widely separated. Most of the colonies are pale translucent pink and the collector's note described some of them as " bright pink (or white)" during life. 918 R. H. Millar on Ascidians from Mozambique

According to Michaeisen (1934) this is a very variabie species. It has been described under several names. Amongst the present material the shorter coionies have zooids 2·0 to 2·8 mm. in Iength and the tall :finger-like colonies have zooids reaching 6 mm. in Iength. The zooids have no diagnostic features and show the characters common to the genus. Larvm are present and these range from 0·36 to 0·54 mm. in length. When fully developed the larvre have the three anterior papillre separated by two median ampullre. One doraal and one ventral media:n ampulla are a.Iso present. The cerebral vesicle contains an ocellus and otolith. The larva is quite large relative to the size of the thorax of the zooid and all the breeding zooids that I have seen contain only a single embryo or larva. Fig. 5.

EudiBtoma mobiU8i (Hsrtmeyer). Zooid. Eudistoma möbiusi (Hartmeyer). Fig. 5. Colella möbiusi Hartmeyer 1905, p. 396, pl. 13, :figs. 2, 3. Polycitor möbiusi Hartmeyer 1912, p. 305, text-:figs. 1-3, pl. 43, fig. 4. ( Polycitor (Eudistoma) möbiusi Michaeisen 1919, p. 73. ;, K nown distribution.-Tanganyika; Mozambique; Zanzibar; Mauritius ;..,U . Madagascar ; Durban ; Cape Province. · .!i Localities.-Inhaca Isiand, two specimens; Mozambique Island, one'~i specimen. · ;:.~ Description.-The three colonies are all rather small, the largest bein~·.l·~ 1·3 cm. in diameter. The basal area of attachment is :Bat and the uppet• i }!t R. H. Millar on Ascidians from Mozambique 919 surface rounded. There may he a slight subdivision of the colony into indistinct lobes, as in one of the specimens from Inhaca Island. In consistency the test is rather soft or semi-cartilaginous and in colour it has a characteristic green-blue suffusion especially in the upper part. The zooids show through the test as darker green-blue spots. Existing accounts leave little to he added to the description of the zooids. In the present specimens the pigmentation is most intense on the anterior part of the thorax. Some of the zooids are sexually mature, having in the Iower part of the abdomen a compact group of testis follicles and a few large oocytes repreaenting the ovary. Unfortunately no fully developed larvm were present, but the most advanced embryo already had a tail and sensory pigment. The trunk of this embryo measured 2 mm. in length and although the larva when fully differentiated, may be shorter, it is clear that E. möbiusi ~as a very large larva. · Eudistorna caeruleum (Sluiter). Fig. 6. Distoma caeruleum Sluiter 1897, p. 14, pl. 2, fig. 4, pl. 3, fig. 14. Polycitor (Eudistoma) caeruleum Hartmeyer, 1909, p. 1431. Polycitor (Eudistoma) caeruleus Michaeisen 1919, p. 73. Sigillina (Eudistoma) coerulea Michaeisen 1934, p. 141. Known distribution.-Natal. Locality.-Inhaca Island, several specimens. Description.-The largest colony is 4·5 cm. in height. All specimens have the club-shaped appearance characteristic of the species, and also the characteristic deep blue-black colour. The surface is smooth and without enerusting matter. Zooids are present only in the upper expanded part of the colony, and are not arranged in any apparent order. In structure the zooids agree with Sluiter's original- description, but the stomach of the present specimens is shorter and wider than that illustrated by Sluiter. The testis is well developed but the ovary is small and no larvm were found. Eudistoma paesslerioides (Michaeisen). Polycitor (Eudistoma) paesslerioides Michaeisen 1914, p. 428; Michael­ sen 1919, p. 73. Known distribution.-Gold Coast, French Congo and Angola, West Africa ; Red. Sea ; Seychelles. Localities.-Inhaca Island, several colonies; Mozambique Island, one colony. Description.-The colonies vary in shape from rather fla.t, a.ln10st . enerusting sheets to thick, cushion-like masses. All of them have a · thick covering of sand and broken shell which aiso penetratea to the · interior of the test. In preserved specimens the length of the zooids depends a good deal on their state of contraction ; well expanded zooids measure about 3 mm. in length. The siphons are quite conspicuous, with strong circular 920 R. H. Millar on Ascidians from Mozambique and longitudinal muscles, but the circular muscles do not foxm a thick sharply defined sphincter on each siphon as in E. angolanum. On each side ofthe thorax there are 25 or more narrow Iongitudinal muscles. This is a greater number than that found by Michaeisen (1915) in any of his variaties of E. paesslet·ioides from West Africa (var. hupjeri-S; var. intermedia-12-14; var. typica-18). But the number is so variabie within the species that the character is apparently not a reliable one. Hastings (1931) described Australian specimens of E. ovatum (Herdman)

Fig. 6.

EudiBtoma caentleum (Sluiter). Different fonns of colony. with only 4-6 longitudinal muscles, and considers that E. paesslerioides is a synonym of E. ovatum. There is still much confusion regarding the validity of these and other closely similar species of Eudistoma which may eventually be reduced to a single species of wi.de distribution in the warm waters of the world. Genus Olavelina Savigny, 1816. Olavelina enormis Herdman. Fig. 7. Olavelina enormis Herdman 1880, p. 725. For synonymy see Michaeisen 1919, p. 71. Known distribution.-Mozambique; Mauritius; Zanzibar; ? Red Sea; Chagos Archipelago ; Cape Province, S. Africa. Locality.-Inhaca Island, one specimen. Description.-The specimen consists of two zooids united at their posterior ends by short stalks and free for the rest of their length. Each zooidis about 1·4 cm. long. The test is clear and the anterior end ofthe body has some blue-violet pigment. According to the colleotor's note the animals in life had a transparent test and olue body. The thorax is short, probably owing to contraction, but has at least 12 rows of stigmata. The abdomen is much langer than the thorax, and contains the long oesophagus, short barrel-shaped stomach and the intestinalloop. The stomach was described by Hartmeyer (1912) as smooth walled marked R. H. Millar on Ascidians from Mozambique 921 by a few longitudinal dark streaks. In the present specimens the stomach has four fairly distinct wide folds, as seen in a transverse section of the gut. The testis consists of many round or pear-shaped follicles grouped beside the Iower part of the intestinal loop. The ovary lies close beside the testis. Fig. 7.

Olavelina enorm-ia Herdman. A, two zooids. B, zooid removed from test. C, transverse section of stomach. D, larva. Developing embryos and fully formed larvre are present in the upper part of the oviduct. The larva measures about 0·6 mm. from the end of the papillre to the base of the tail. There are two dorsal and one ventral papillre arranged in a triangle. Both otolith and ocellus are present. Family Didemnidae Verrill, 1871. Genus Diplosoma Macdonald, 1859. Diplosoma modestum Michaelsen. Fig. 8. Diplosoma modestum Michaeisen 1920, p. 67. For synonymy see Michaeisen 1920, p. 67. Known dist1·ibution.-Seyche1les; ? Zanzibar. Locality.-Inhaca Island, one specimen. Description.-The colony is 9 cm. in greatest diameter, and 0·5 cm. thick. It forms a soft and fleshy sheet of a pale pink-grey colour. The collector's note describes the zooids in life as bright yellow. Except for the absence of bladder-celis in the test, the specimen agrees well with 922 R. H. Millar on Ascidians from Mozambique Michaelsen's account. The present colony contains larvre embedded in the basalpart of the test. They range from 0·76 to 0·80 mm. in Iength from the end of the papillre to the base of the tail, and are similar to the larvre of other species of Diplosoma.

Fig. 8.

Diplosoma modestum Michaelsen. Larva. Genus Didemnopsis Hartmeyer, 1903. Didemnopsis sansibaricum Michaelsen. Didemnopsis sansibaricum Michaeisen, 1920, p. 6. K noum distribution.-Zanzibar. Locality.-Mozambique Island, two colonies. Description.-These specimens are obviously identifiable with D. sansibaricum. In one colony the zooiels have a very short tubular atria! siphon and in the other a simple slit on the dorsal surface of the thorax. Michaeisen noted that in the zooiels which he examined the atria! siphon was scarcely visible but that it was more conspicuous in the first thoraoio bud of the tailed larva. Genus Didemnum Savigny, 1816. 1Didemnum psammatodes (Sluiter). Leptoclinum psamathodes Sluiter 1895, p. 171, pl. 7, figs. 9-11. For synonymy see Michaeisen 1920, p. 22. Knoum distribution.-With this, as with many species of Didemnum it is very difficult to know whether all existing recórels refer to a single species and to what extent records of other species should he referred to this one. The distribution is therefore uncertain ; a number of variaties of D. psammatodes have been described from Zanzibar, Mozambique, the Seychelles and other parts of the western Indian Ocean. R. H. Millar on AscidiailB from Mozambique 923 Locality.-Mozambique Island, several colonies. Description.-The colonies are grey, and although of a sheeting form are rather fieshy. Spienies are quite plentiful and are small, most being 15-18 fL in diameter. The rays are numerous butsoshort that under low magnification the spienies have an almost spherical outline instead of the stellate outline which the spienies have in many species of Didemnum. In the size and shape of their spicules, these colonies most resembie var. ianthinum (Sluiter). Larvro are present in the colonies. These are about 0·36 mm. in length from the end of the papillro to the base of the tail, and are of the usual didemnid type with four anterior ampullro on each side and three median papillro. Fig. 9.

Ascidia incrassata Heller. A, individual removed from test. B, dorsa.l tubercle.

Family Ascidüdae Herdman, 1880. Genus Ascidia Linnaeus, 1767. Ascidia incrassata Heller. Fig. 9. Ascidia incrassata Heller 1878, p. 88, pl. 2, fig. 8. For synonymy see Michaeisen 1918, p. 57. Knourn distribution.-Oape Town and Simons :Bay, South Mrica; Mozambique. Locality.-Inhaca Island, several specimens. Description.-The largest specimen is 6 cm. long, excluding the siphoilB which themselves may be nearly 2 cm. long. Some sand and broken shell is stick.ing to the surface of the test. When removed from the test the body is seen to be grey-pink and the sipbons red. There are quite strong circular muscles on the siphons, and near the doraal and ventral edges of the right side of the body. Elsewhere muscles are not strongly developed. The dorsal tuberele has the inrolled homs charac­ teristic of the species. In two specimens the tentacles numbered 160 924 R. H. Millar on Ascidians from Mozambique and at least 190 respectively. Michaeisen (1918) has already noted the differences between the number of tentacles (150) which he found and the relatively small number (40-70) found by Heller (1878), Herdman (1882), Traustedt and Weltner (1894) and Hartmeyer (1911). The fact that Michaelsen's specimens were from Mozambique and all specimens described by the other authors from Cape Province, together with the corresponding differences in the number of tentacles, might suggest that specimens from the two localities are of different species. But so far there is not enough evidence to confirm the suggestion. Ascidia arenosa Hartmeyer. Fig. 10. Ascidia sabulosa Sluiter 1898, p. 45, pl. 6, figs. 2-5. Ascidia arenosa Hartmeyer 1909, p. 1404. K1UJW11, distribution.-Natal. Locality.-Inhaca Island, several specimens. Description.-The largest specimen is 3·2 cm. long and 1·9 cm. wide (dorsi-ventrally). Most of the specimens are laterally flattened. The sipbons are fairly close together at~he anterior end of the body, and are

. ·~\

A ~8

Ascidia arenosa Hartmeyer. A, individu.al removed from test. B, dorsal tubercle. rather short. There is an almost complete coating of sand on the surface of the test and some embedded within the test. In a specimen 1·5 cm. long there are 70 tentacles and about 40 internallongitudinal bars on each side ofthe branchial sac. All speciniens examined have a simple U-shaped or C-shaped doraal tuberele with the open interval facing forwards. This species is readily distinguished from A. incra.ssata by its enerusting sand, smaller number of tentacles, and simple doraal tubercle.

Family Botrrllidae Verrill, ~871. Genus BotryllWJ Gaertner, 1774. BotryUWJ planWJ (Van Name). Fig. 11. Botrylloides nigrum var. planum+B. nigrum var. conoolor Van Name 1902, pp. 377, 378, pl. 53, figs. 53, 55, pl. 59, fig. 110. R. H. MilJar on Ascidians from Mozambique 925 For synonymy see Van Name, 1945, p. 222. Known distribution.-West Indian region. Locality.-Inhaca Island, one specimen. Description.-The colony is a fiat enerusting mass on which the dark purple zooids show up against a paler background. The zooids are arranged in moderately long double rows, a number of which converge to a single round or oval common cloaca! opening. There are about 10 short oral tentacles, 8-10 rows of stigmata, and 10-12 longitudinal folds on the stomach. The stomach has a large and conspicuous curvéd caecum. On each side of the body is a posterlor lobed testis and an anterior ovary with a single large egg. .. Fig. U!

c Botryllus planua (Va.n Na.me). A, arrangement of zooids round a common cloaca! opening. B, zooid with testis and ovary. C, part of gut.

Although this species is not recorded from nearer than the West lndies, I can scarcely doubt the identifi.cation of the specimens from Inhaca as they agree very closely with Van Name's (1945) description.

Family Styelidae Sluiter, 1895. Genus Symplegma Herdman, 1886. Symplegma viride Herdman. Symplegma viride Herdman 1886, p. 144, pl. 18, figs. 7-14. For synonymy see Van Name 1945, p. 232. Known di8tribution..-The species is widely distributed in tropical waters, including the West Indian region, Ceylon, lndonesia, North Australia, Mauritius, and Tanganyika. Locality.-Inhaca lsland, one specimen. Remarks.-I have nothing to add to the description of this well-known species. 926 R. H. Millar on Ascidians from Mozambique Genus Styela Fleming, 1822. Styela marquesana Michaeisen. Fig. 12. Styela marquesana Michaeisen 1918, p. 27, pl., fig. 4, text-fig. 5. Millar 1955, p. 207, fig. 32. Known distribution.-Mozambique; Durban. Locality.-Inhaca Island, several specimens. Description.-The specimens are allofan upright form with the oral si phon terminal and the atria! sipbon a bout one-third of the body length from it. In a specimen 2·5 cm. long there are about 40 oral tentacles. The dorsal tuberele has a simple C-shaped slit with the open interval

,Fig. 12.

A IJJB

Styela mMqueBana Michaelsen. A, individual, showing gonÎI.ds of Ieft side. B, gut. facing forwards and the horns not inrolled. The arrangement of the longitudinal branchlal bars in a specimen 2·5 cm. long is : dorsal line 6 (14) 5 (13) 5 (14) 4 (10) 4 endostyle. There ar'e about 25 folds on the wall of the stomach. Michaeisen (1918) found 28-30 folds in his type specimens but I have previously noted the presence of only 21-23 folds in specimens from Durban (Millar, 1955). The number, structure and arrangement of the gonads, which Michaeisen evidently regarded as an important diagnostic feature, are the same as in the type specimens.

Genus Polyandrocarpa Michaelsen, 1904. Polyandrocarpa tincta (Van Name). Fig. 13. Michaelsenia tincta Van Name 1902, p. 381, pl. 54, figs. 61, 63, pl. 59, fig. 109. ? Eusynstyela hartmeyeri Michaeisen 1904, p. 38. For synonymy, see Van Name 1945, p. 250. K nown distribution.-Bermuda and Florida ; Senegal ; ? Red Sea. Locality.-Inhaca Island, several colonies. Description.-The colonies are 2-4 mm. thick and form low enerusting masses of a pink or pink-purple colour. The zooids are embedded in the R. · H. Millar on Ascidians from Mozambique · 927 common test from which the low sipbons alone project slightly. In the branchial sac of a large zooid the bars are arranged as follows : dorsal line 0 (12) 1 (7) 2 (10) 2 (10) 1 endostyle. Many zooids have fewer bars on the folds than this, and in some the most ventral fold is missing on each si de. There are 14-16 folds on the wall of the stomach, which bas a small hooked caecum. Nçme of the zooids which I examined had any trace of gonads. Fig. 13.

A

Polyandrocarpa tincta (Van Name). A, gut. B, doraal tubercle.

Remark~.-There seems to be little reasou for separating P. tincta and Eusynstyela hartmeyeri and I believe that they should be united, the former name having priority.

Polyandrocarpa inhacae, sp. n. Fig. 14. Diagnosis of species.-Colony of zooids united only by a basal stolon. Zooids with 20-30 oral tentacles ; a longitudinal slit-like opening to the dorsal tuberele ; neural gland with a rounded mass on each side of the ganglion ; branchlal sac with two or three slight folds on each side ; each fold with 5-Slongitudinal bars ; a bout five longitudinal bars between 928 R. H. Millar on Ascidians from Mozambique folds ; stomach with about ten folds and à short pyloric caecum. Larva with trunk about 1·2 mm. long. Locality.-Inhaca Island, one colony. Description.-The colony consists of a fairly compact mass of zooids united by a system of basal stolons. ·· The zooids are erect, rectangular in outline or club-shaped with their lower narrow end joining the stolon. Most of the zooids are 4-6 mm. in height but a few reach 8 mm. At their upper end the zooids have the two small conical papillre repreaenting the siphons. Except for the ends of the sipbons thc whole surface of the zooids and the stolons is covered with adhering sand and broken shell.

Fig. 14.

D

Polyandrocarpa inhacae sp. n. A, colony. B, zoqid, showing arrangement of gona.ds on left side. \ C, dorsal tubercle, ganglion, Émd divided neura.l gland. D, gut. ·,l

The bodywallis thin with many closelyspaced very alender longitud.inal t~ and circular muscles. Of the two sipbons the oral is slightly the longer 11 and wider. Th~re are 20 t~ 30 m~derately l?ng oral t?ntacles.. The ,~l.~ dorsa.l tuberele IB na.rrow With a. Bimple straight or slightly sm.UOUB'~ longitudinal slit. Immediately posterlor to the tuberele lies the globular~~~ ganglion, and on each side of the ganglion a single mass of neural glandi~ tissue.. I have not found .how these apparently isolated masses of tissueiJ are umted or connected With the doraal tubercle. · fi' -~~~ ,ft:;-<' R. H. Millar on Ascidians from Mozambique 929 Each side of the branchial sac has three or occàsionally only two low folds. In a large zooid the longitudinal bars on the folds have the following arrangement : dorsalline 0 (8) 5 (5) 5 (5) 8 endostyle. In a small zooid with only two folds on each side this is the arrange­ ment: dorsalline 1 (7) 5 (5) 5 endostyle. ,'.Phè ,dOI'Sal lamina is a narrow smooth-edged membrane. The endo­ style is also rather narrow. The oesophagus is short and slightly curved, and the stomach ovoid with about ten longitudinal folds and a short pyloric caecum. The intestine is gently curved and the rectum extends forwards to about half way along the branchlal sac. Unfortunately the gonads were poorly developed. An irregular line of sm.all gonads extends on each side of the body, roughly parallel to the endostyle, and another curved line of gonads in the posterlor part of the body on. each side. I could not determine whether the gonads are hermaphrodite or unisexual. Some zooids contain a larva and never more than one. This is very large, the trunk measuring about 1·2 mm. from the end of the papillm to the ba-Ee of the tail. There are three very short papillm and a short

Family Pyuridae Hartmeyer, 1908. Genus Pyura Molina, 1782. Pyura sansibarica Michaelsen. Fig. 15. Pyura sansibarica Michaelsen, 1908, p. 251, pl. 2, figs. 27-29. K nown distribution. -Zanzibar. Locality.-Inhaca Island, two specimens. Desc~ption.-The smaller and more typical specimen is 1·2 cm. long and 1·2 cm. high; the la.rger specimen is 3·5 cm. long and 2·8 cm. high. On the dorsal surface are the twó inconspicuous siphons. Most of the surface of the test has a coating of sand and broken !)heil. Short spines are present on and near the sipbons and are visible as a fringe projecting from the ends of both siphons: These spines on the dorsal surface of the body were also noted by Michaeisen (1908). There are 12 oral ten- A.M.N.H. ser. 12, vol. ix. 59 930 R. H. Millar on Ascidians fi:om Mozambique tacles in the smaller animal and about 24 in the larger. The dorsal tuberele is C-shaped either with slightly inrolled or .with straight horns. Details of the branchial sac agree with Michaelsen's account. The arrangement of the longitudinal bars in the larger specimen is as follows : doraal line 4 (19) 4 (18) 4 (25) 4 (25) 5 (19) 6 (14) 5 endostyle. The stigmata are small and oval and are crossed by para-stigmatic transverse bars. In the branchial walls and also in part of the body wall of the larger specimen there are many white spherical or irregular bodies 0·1 to 0·3 mm. in diameter. These bodies might be regarded as spicules but there is notrace afthem inthesmaller specimen and I do not know what they are.

Fig. 15.

Pyura sansibmica Michaeisen A, individual removed from test.. B, tentacle. C, dorsal tubercles of the two specimens.

The secondary loop of the gut is more open in these two specimens than in the type specimen. The left gonad lies entirely within the primary loop of the gut and the right gonad accupies a corresponding position on the other side. Remarks,-The present specimens differ in some respects from the type specimen, particularly in the coating of sand on the test, the more open secondary intestinal loop and the presence, in one specimen, of spicule-like bodies. The similarities, however, are more important than the di:fferences and I have little doubt that we are dealing with P. mnsibarica. Genus Herdmania Lahille, 1887. Herdmania momus (Savigny). Oynthia momus Savigny, 1816, p. 143, pl. I, fig. 2, pl. 4, fig. I. Forsynonymy see Van Name, 1945, p. 341. Knourn distribution.-The species is widely distributed in warm tbraughout most of the world. · Locality.-Mozambique Island, one specimen. R. H. Millar on Ascidians from Mozambique 931 Description.-The specimen is quite typical of the species, and shows a good development of the very characteristic spicules.

TABLE I.

Soutb Indian West Indonesia Indian Other areas. Africa. Ocean. region. ------A. altarium ········ 0 0 + 0 0 A. petrense ...... 0 + 0 0 0 A. lubriourn + 0 0 0 0 P. macropltyllum .... 0 + 0 0 lVeatern Austmlia. E. rhodopyge 000 ••• + 0 0 0 0 E. möbiusi + + 0 0 0 E. caerule·um ... , .... + 0 0 0 0 E. paeaslerioides , . , . 0 + 0 0 West Afri.ca ; Red Sea. 0. enormis ...... , .. , + + 0 ? RedSea. D. modestum ...... 0 ·+ 0 0 0 D. sansibaricmn .... 0 0 0 0 Zanzibar. D. p.mmmatmles .... 0 + 0 0 0 A. ·incrassata + 0 0 0 0 A. arenosa ...... + 0 0 0 0 B. planus ...... 0 0 0 + 0 S. viride ...... 0 + + + North Australia. 8. marquesana ...... + 0 0 0 0 P. tincJa ...... 0 0 0 + West Africa ?Red Sea. P. sansi.ban'ea ...... 0 0 0 0 Zailzibar. H.momus ...... + + + Red Sea; Wastem + Pacific, Eastem Austra!ia.

Nnte.--Indian Ocean bere denotes part.q of the region other than the coast of Mozambique and Tanganyika.

Ajfinities of the fauna. Table 1 shows the further distribution of the species in the collection, excluding the new species. From this it can he seen that 45 per cent ofthe species are already known from farther south on the African coast, 46 per cent from other parts of the Indian Ocean, 20 per cent from the West Indian region, and 15 per cent from Indonesia. Twentyper cent of the known species have only been recorded from the warmer parts of the western Indian Ocean and East Mrican coastal waters. There is a small pan-tropical element best represented by Symplegma viride and Herdmania momus.

SUMMARY. An account is given of a collection containing 21 species of ascidians from the shores of Mozambique, East Mrica. Only one new species, Polyandrocarpa inhacae, is described. The ascidian fauna as represented by this collection shows affinities mainly with South Africa and with other parts of the Indian Ocean. 59* 932 R. H. Millar on Ascidians from Mozambique

REFERENCES. HARTMEYER, R. 1911. Die Ascidien der deutschen Südpolar-Expedition, Dtsch. Siidpol. Exped. 12, 403. 1912. Die Ascidien der deutschen Tierfsee-Expedition. Wiss. Ergebn.' Valdivia •; 16, 225. . . HASTINGS, A. B. 1931. Tunicata. In Graat Barrier Reef Expedition 1928-29: Sci. Rep. 4, 69. HELLER, C. 1878. Beiträge zur nähern Kenntniss der Tunicaten. S. B. AT.:ad. Wiss. Wien. 77, 83. HERDMAN, W. A. 1882. Report on the Tunicata collected during the voyage of H.M.S. "Challenger" during the years 1873-1876. Part I. Ascidire sirnplices. In Thompson, C. W. and J. Murray. Report on the scientific rasults of the voyage · of H.M.S. "Challenger" during the years 1873-1876. Zoology 6, 296 pp. MICHAELSEN, W. 1908. Die Pyuriden (Ha1ocynthiiden) des Naturhistorischen Museums ·.. zu Hamburg. Jahrb. Wiss. Anst. Hamburg 25, 227. ..: 1915. Tunicata. In Beiträge zur Kenntnis der Meerasfauna Westafricas. 1, 312. • :. 1918. Die ptychobranchen und diktyobranchen Ascidien des westlichen Indischen·,;: Ozeans. Jalirb. Wiss. Anst. Hamburg. 35, 73 pp. ·• 1919. Die krikobranchen Ascidien des westlichen Indischen Ozeans: Claveliniden <~ und Synoiciden. Jahrb. Wiss. Anst. Hamburg 36, 69. 1920. Die krikobranchen Ascidien des westlichen Indischen Ozeans : Jahrb. Wiss. Anst. Hamburg 37, 74 pp. 1921. Ascidien von westlichen Indischen Ozeans aus dem Reicbsmuseum zu Stockholm. Ark. Zool. 13, 25. , 1934. The ascidians of the Cape Province of South Africa. Trans. roy. Soc; S.Ajr. 22,129. . MILLAR, R. H. 1955. On a collection of ascidians from South Mrica. Proc. zool. Soè.<;l Lond. 125, 169. ···':i SLUITER, C. P. 1897. Beiträge zur Kenntnis der Fauna von Süd-Africa. 2. Tunicaten:: ~ Zool. Jahrb. 11, 64 pp. 'd ;~ 1909. Die Tunicaten der Siboga-Expedition. Part 2. Die roerosomen Asm ièn;, cl Siboga Exped. 56 b, 112 pp. TnAuSTEDT, M. P.A. & \\'ELTNER, W. 1894. Bericht iiber die von Herrn. Dr. Bander . gesamrne1ten Tunicaten. Arch. Naturgesch. 60, 10. VAN NAME, W.G. 1945. The North and South Arilerican ascidians. Bull. Amer. Mus.··; nat. Hist. 84, 476. pp.

CORRECTION. In Ann. Mag. Nat. Rist., vol. ix, No. 105, p. 673, end of first paragraph, for " Cambriates '' raad " pra-Cambrian ''.