The Fauna and Geography of the Maldive and Laccadive
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/ Supplement I. will be published on March i, igo^. The Fauna and Geography of the Maldive and Laccadive Archipelagoes Being the Account of the Work carried on and of the Collections made by an Expedition during the years 1899 and 1900 Edited by Gardiner, M.A. J. Stanley Fellow of Gonville and Caius College and late Balfour Student of the University of Cambridge. VOLUME II. PART IV. With Plates LXVII—LXXXVII and Text-Illustrations 127—139 Cambridge : at the University Press. Cambridge University Press Warehouse C. F. Clay, Manager. Lane, E.G. London : Ave Maria Price Fifteen Shillings net. V.2 ^pt 4 iVith the compliments of the Syndics of the Cambridge University Press. m —^_ m The Fauna and Geography of the Maldive and Laccadive Archipelagoes VOLUME II. PART IV. CAMBRIDGE UNIVERSITY PRESS WAREHOUSE, C. F. CLAY, Manager. iLonSon: AVE MARIA LANE, E.G. AND H. K. LEWIS, 136, GOWEE STREET, W.C. ffilasgoto: 50, WELLINGTON STREET. ittqjjiS: 1'- A. BROCKHAUS. ifttto iorfe: THE MACMILLAN COMPANY. Bombag anil Calcutta: MACMILLAN AND CO., Ltd. [All riiiihts resiTVed.] .F3 The Fauna and Geography ^; of the c Maldive and Laccadive Archipelagoes ' Being the Account of the Work carried on and of the Collections made by an Expedition during the years 1899 and 1900 Edited by J. Stanley Gardiner, M.A. Fellow of Gonville and Caius College and late Baltour Student of the University of Cambridge. VOLUME II. PART IV. With Plates LXVII—LXXXVII and Text-Illustrations 127—139 Cambridge : at the University Press. 1905 : CAMBRIDGE PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS. CONTENTS OF VOL. II. PAET IV. Reports. 1. The Alcyonaria of the Maldives. Part III. The Families Muriceidae, Gorgonellidae, Melitodidae, and the Genera Pen- nattda, Eunejihthya. With Plate LXVII . 807 By Sydney J. Hickson, M.A., D.Sc, F.R.S. 2. Marine Crustaceans. XIV. Paguridae. With Plate LXVIII . 827 By Major Alcock, F.R.S. 3. Hydroids. With Plate LXIX 836 By L. A. BoRRADAILE, M.A. 4. Notes on Parasites ........ .846 By A. E. Shipley, M.A., F.R.S. 5. Ehynchota ........... 847 By W. L. Distant. 6. Marine Crustaceans. XV. Les Alpheidae. (Plates LXX—LXXXVII et Texte-Figures 127—139.) 852 Par Professeur H. CoDTifeRE. THE ALCYONARIA OF THE MALDIVES. PART III. THE FAMILIES MURICEIDAE, GORGONELLIDAE, MELI- TODIDAE, AND THE GENERA PENNATULA, EUNEPHTHYA By Sydney J. Hickson, M.A., D.Sc, F.R.S., Beyer Professor of Zoology in the Victoria University of Manchester. (With Plate LXVII.) Our knowledge of the Alcyonarian fauna of the Indian Ocean is very imperfect. It is true that Gray, Milne-Edwards and Haime and many other writers of the earlier part of the last century have described species from the " East Indies," but the descriptions are in most cases so supei-ficial and the localities given so vague or doubtful that their records are of very little value. The only modem paper on the subject is that by Ridley (17) on the Alcyonaria of the Mergui archipelago. Neither the "Astrolabe," "Alert," the "Challenger," nor the "Gazelle" visited the district, and the Alcyonarians collected by the naturalists of the "Investigator" have not yet been described. It is not sui-jDrising therefore that of the thirteen species of Gorgonacea described in this memoir from the Maldives no less than six appear to be new to Science. The classification of the Gorgonacea is still in a very unsatisfactory condition, but a thorough investigation of the anatomy of some of the leading genera is necessary before it can be placed on a more scientific basis. In the mean time I have decided to adopt as closely as possible the classifi- cation used by the authors of the Challenger volume on the Alcyonaria. According to that classification then the Gorgonacea collected by Mr Gardiner belong to the families Briareidae, Melitodidae, Muriceidae and Gorgonellidae. The important families of Gorgonacea which, according to this classification, are not represented in the collection, are the Sclerogorgiidae, Coralliidae, Dasygorgidae, Isidae, Primnoidae^ , Plexauridae and Gorgoniidae. The absence of any precious corals may have been disappointing but not surprising, as the family seems to be confined to regions of cooler water than that of the Maldives. The only statement we have concerning the occurrence of the precious coral in Indian seas is that made by Alcock (i. p. 291), "At one spot, not far from Trincomalee, M'Ai-dle found abundance of a beautiful pink coral which appears to be identical with the precious coral." The absence of Primnoidae^ and Dasygorgiidae is not surprising, as the members of these families are with a few exceptions usually found in deeper water than any investigated 1 As I wag correcting the proofs of this paper Mr Gardiner laris (W. and S.) discovered by the Challenger in 600 fathoms sent me a fragment (2.5 mm. long) of a Primnoid from Mahlos off the Kermadecs. Atoll, 24 fathoms. It is closely related to Stachyodes regu- G. II. 104 808 SYDNEY J. HICKSON. by Mr Gardiner. The absence of Isidae however is noteworthy. Isis was described by Steenstrup (fide W. and S.) from the Indian Ocean. It is common in some shallow water localities in the Pacific Ocean and coasts of the Malay archipelago. As regards the absence of Plexauridw and Gorgoniidae it may be remarked that, although there are no pronounced types of these families in the collection, some of the specimens approach them very closely in their general characters. One specimen of Gorgonella verriculaia, for example, has such a thick coenenchym and such a black flaky axis that it would have been placed with certainty in the family Plexauridae had it not been found in the same collection with the other specimen which is clearly a Gorgonella. The new speciea Elasmogorgia flexilis again might with justice be placed in the family Gorgoniidae, the slight roughness of the surface being the only character at present known which justifies the inclusion of the genus in the family Muriceidae. The boundary line between the family Muriceidae and the Gorgoniidae and that between the Plexauridae and the Gorgonellidae are quite artificial ; and it is probable that a rearrangement of the genera included in these four families will be found necessary in the near future. The species of Gorgonacea described in this paper are Family Muriceidae. Acanthogorgia flabellum n. sp. Behryce sp. ? Acamptogorgia horrida n. sp. Elasmogorgia flexilis n. sp. Muricella perramosa (Ridley). Acis sp. ? Family Gorgonellidae. Gorgonella verriculaia (M. E. and H.). Juncella juncea (Pall). Juncella flexilis (Studer). Juncella elongata (Val). Scirpearia fareata n. sp. Scirpearella indica n. sp. Family Melitodidae. Melitodes variabilis n. sp. I have also described briefly the only Pennatulid sent to me, Pennatida murrayi Kolliker, and a specimen of Nephthyid I received too late to be included in Part I, Eunephthya maldivensis n. sp. The species of the family Briareidae were described in Part I (9). THE ALCYONARIA OF THE MALDIVES. 809 Family Melitodidae. Melitodes vai~iahiUs n. sj). Fig. 11. Locality. This species may be said, in general terms, to occur throughout the Archipelago in shallow water. In my last paper on the Alcyonaria of the Maldives I published a preliminary note on these specimens, in which I pointed out the difficulty of the problem they present to the systematist. Since then I have made a further careful anatomical investigation of the specimens, not sufficient perhaps to enable me to write very definitely and clearly on the subject, but sufficient to convince me that without further researches on the reef I should not be justified in recognising more than one species. The problem presents itself to my mind in this form. There are three characters in which the specimens show pronounced variations: 1. the colour of the spicules, 2. the length of the internodes, 3. the size of the spicules. These characters are, so far as I can judge, fairly constant within the individual colonies. All the specimens being fragmentary, however, this is a point that cannot be determined with absolute certainty. 1. The colour of the spicules may be a good character for the determination of a species of Alcyonarian, but as we know that at the Cape of Good Hope (Hickson 7) the spicules of the genus Melitodes do show striking variability in colour, and that in another Alcyonarian from the Maldives Ghironephthya variabilis (9) there are very remarkable differences in the local distribution of spicule colour, it is at least very doubtful whether in this species the colour scheme of the spicules can be regarded as a good specific character. 2. The length of the internodes is just one of those characters which varies with local circumstances. It varies in an individual colony, the internodes of the main stem and primary branches being always shorter in proportion to their diameter and to the length of the nodes, than they are in the terminal branches. This, therefore, is not a character that can be used for determination of species without exact and precise knowledge of the local circumstances. 3. That the size of the spicules varies proportionately with the diameter of the intemode, is, as a general statement of the facts, I believe, true. Melitodes variabilis is one of those species in which the size of the spicules from any one part of an intemode varies considerably. It is only possible, by measuring the length of a considerable number of spicules from one intemode and taking an average of their length, to arrive at any conclusion as to the figure to be taken to represent the length of the spicule of that intei'node. To feel strict confidence in the statement I have made it would be necessary to compare a large number of such averages from internodes of the same and different colonies.