96 OKHAMANDAL MARINE ZOOLOGY REPORT PART II 



The fact that it has been possible to identify seventy-four per cent, of these species 

 with previously described forms clearly indicates the progress that has been made 

 in recent years in our knowledge of the Sponges of the Indian Ocean, especially when 

 we consider that Mr. HornelPs collection was made in a locality from which, so far 

 as I am aware, no sponges have hitherto been recorded. 



As might naturally be expected, a large proportion of the previously known 

 species are identical with more or less well-known Ceylon forms [cf. Dendy 

 1905]. The commonest species in the collection is Esperella plumosa (Carter), 

 which attains a large size and has a very fully developed and very beautiful 

 spiculation. Other common and characteristic Indian Ocean species are Myriastra 

 haeckeli, Donatia seychellensis, Chondrilla australiensis, Tetilla dactyloidea, Tetilla 

 hirsuta, Phakellia donnani, Aulelta lyrata, lotrochota baculifera, Clathria comllitincta, 

 Clathria spiculosa, Raspailia fruticosa, Spirastrella vagabunda, Placospongia carinata 

 and Hippospongia clathrata. 



Of the fifteen new species, Tetilla pilula, T. barodensis, Guitarra indica, Psam- 

 mochela elegans (for which a new genus is proposed), Polymastia gemmipara and 

 Megalopastas retiaria may be mentioned as exceptionally interesting forms. 



The scarcity of true Horny Sponges (Euceratosa) in the collection is remark- 

 able. There is no true bath sponge and, indeed, only one representative of the 

 family SpongiidaB, viz., the common but useless Hippospongia clathrata. On the 

 whole, however, the Sponge-Fauna of Okhamandal is undoubtedly a rich one, and 

 I am very glad to have had the opportunity of investigating it. 



All the specimens in the collection seem to have come from shallow water, the 

 greatest depth recorded being seventeen fathoms. A considerable number of them 

 were growing upon the large, branching, parchment-like tubes of a polychsete 

 worm,* which appears to be extremely common. It is unfortunate that so many 

 of the specimens were originally preserved in formalin, a medium which is 

 entirely unsuited for sponges and in which they undergo extensive maceration. 



As regards the classification employed in this Eeport it will be observed that 

 certain innovations have been introduced. The Axinellidse are included in the 

 Haploscleridse, and the Spirastrellidse, Clionidse and Suberitidaa are placed in the 

 Sigmatotetraxonida. I cannot attempt to justify these changes in this place, 

 but must refer the reader to my Reports on the Sponges of the Sealark Expedition, 

 now in course of publication, and to future publications by myself and my 

 colleague, Mr. R. W. H. Row, in which we hope to discuss the question of the 



* I am indebted to Dr. J. H. Ashworth and Professor Fauvel for the information that this worm 

 is a species of the genus Eunice, possibly Eunice tubifex Crossland. [A photograph of a forest of the 

 tubes of this worm draped with masses of zoophytes and polyzoa, as seen at extreme low water on 

 the Kiu littoral, Beyt harbour, is reproduced as Plate VI. in "Marine Resources of Okhamandal," 

 in Part I. of this Report. J. H.] 



