412 PEECY SLA DEN TKUST EXPEDITION. 



Of the above, uo fewer than 17 species and 37 specimens come from the Seychelles 

 Archipelago (chiefly Coetivy and Amirante). Six species and nine specimens come 

 from the Chagos Archipelago (Salomon and Egmont). 



I have marked four species as new : FteraeoUdia annulata, FhylUdiopsis carinata, 

 CeratophylUdia grisea, and Miamira magnifica. It is possible that the last three of 

 these may prove to be merely varieties of Ph. papilligera, Bergh, C. africana, Eliot, 

 and M. sinuata, van Hasselt. But even so, they still present points of interest, for the 

 Phyllidiopsis, if not new, is identical with a species found in the Atlantic (Gulf of 

 Mexico) ; the large soft globules on the back of C. grisea exhibit in a more highly 

 developed form the curious conformation described for C. africana ; and the coloration of 

 M. magnifica is remarkable for its brilliancy even among Indo-Pacific Nudibranchs. The 

 chief morphological interest of the collection lies in the eleven specimens of Doridoeides 

 gardineri, a doridiform cladohepatic nudibranch of most unusual structure, which has 

 already been described in detail by Mr. Evans and myself in the ' Quarterly Journal of 

 Microscopical Science ' (March 1908). 



The lacunae in the collection are striking. The common Indo-Paciflc genera Melibe, 

 Bornella, Nembrotha, and Placobranchus are entirely absent. There is only one 

 Jilolid, and the genera Elysia, Asteronotus, Chromodoris, Ceratosoma, Trevelyana, and 

 Phyllidia, usually numerous in these waters, are represented by one specimen each. 



The Indo-Pacific, especially the shores of East Africa, Ceylon, and the Malay 

 Archipelago, is known as the region where Nudibranchs attain their greatest size and 

 brilliancy. Judged by this standard the individuals in the present collection are small, 

 especially Sclerodoris, Carminodoris, Platydorls, Asterouottis, Ceratosoma, Phyllidia, 

 and Rexabranchus. Only Thordisa, Kentrodoris, Iliamira, and Orodoris can be said to 

 be represented by well-grown specimens. 



Deductions as to the distribution of Nudibranchs can be made from a single collection 

 only with great reserve. Mr. Gardiner informs me that he did little reef-collecting in 

 the Seychelles, except at Coetivy, which may explain the absence of some common 

 forms. Also many species are known to appear on the coast for a few days to spawn 

 and then retire *, so that collecting at different times of the year may yield different 

 restdts both as to the size of individuals and number of sj)ecies. The present series 

 of specimens supports a conclusion suggested by collections made previously by 

 Mr. Gardiner in the Maldive and Laccadive Islands, by Mr. Crossland in the Cape 

 Verde Islands, and by myself in Samoa — namely, that the Nudibranch fauna found 

 round archipelagos which have not been united to any considerable mass of land in 

 recent times is usually not so rich as that of neighbouring mainland shores, and does 

 not afford such large specimens. But the collection from Mauritius described by 

 Bergh consists of 32 species and indicates no material difference from the fauna of 

 the East African coast. A small collection from Christmas Island, lying to the south of 



* I have observed this habit in Ceratosoma, Melihe, Trevelyana, and various species of Aplysia and Pleuro- 

 branchus. 



