132 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Mr. Crossland, in a paper on the (Ecology and Deposits of the 

 Cape Verd Marine Fauna (Proc. Zool.' Soc. London, 1905, vol. i, 

 pp. 170-186), points out that the islands lie in the path of the 

 southern division of the Gulf Stream, which is joined by another 

 current from near the Straits of Gibraltar. Both of these are cold 

 currents, the warm stream from the Gulf of Guinea passing a little to 

 the south of the islands. The above list is quite in keeping with 

 this system of currents, for there is a marked absence of characteristic 

 tropical forms, whereas the Mediterranean element is large, and 

 species recorded from the West Indies and tropical Atlantic are 

 represented. Probably this western element is really larger than it 

 appears to be, for our knowledge of West Indian Nudibranchs is very 

 imperfect, and hardly twenty have been identified with certainty. 

 It is also probable that many of the Mediterranean forms are not 

 specially Mediterranean, but also found in the Azores, Canaries, 

 Madeira, etc. 



The lists of molluscs given by Rochebrune (" Materia ux pour la 

 Fauna de I'.lrchipel du Cap Vert," in Nouvelles Archives du Museum 

 d'Hist. Nat. Paris, 1881, ser. ii, tome iv) yield much the same 

 result. Of 201 molluscs, 21 are recorded only from the islands, 

 5 from the coast of America, 16 from European seas, and 70 from the 

 Mediterranean; while of 285 marine invertebrates of all kinds, 48 are 

 recorded only from the islands, 23 from the west coast of America, 

 and 91 from the Mediterranean. Rochebrune mentions only one 

 Nudibranch, PeUodoris Sauvagei, which is perhaps a colour variety of 

 P. crucis. 



Regarded as tropical Nudibranchs, the present collection offers 

 a remarkable contrast with the forms found in the corresponding 

 latitudes of the Indo-Pacific. There are no specimens of Platydoris, 

 Bornella, Kentrodoris, Hexahranchus, Phyllidia, Trevelyana, or Adero- 

 notus, and the Chromodorididae are represented by only one small 

 species. The first two of the above-mentioned jicnera are recorded 

 from the West Indies, but the rest have not been found in the 

 Atlantic, though the "Talisman" obtained a Phyllidiopsis in the 

 Bay of Biscay. Mr. Crossland (I.e.) also notices the absence of large 

 and highly coloured Planarians, which are very abundant in the 

 Indo-Pacific. In many parts of that ocean, for instance, Zanzibar 

 and the east coast of Africa, the coast in sheltered parts consists of 

 flat, table like coral reefs, which house an incredible amount of 

 marine life. Alcyonarians are abundant, and sometimes form a living 

 carpet. In the Cape Verd Islands the conditions are widely different : 

 Alcyonarians and corals are rare, and the organic rocks are formed 

 chiefly of NuUipores and Vermetm between tides, and below tide- 

 marks of Liihothamnion and great quantities of a Foraniiniferan. 



As we have no information about the Nudibranchs of the West 

 African coast between the Cape Verd Islands and the Cape of Good 

 Hope, it would be rash to assume that the present collection is typical 

 of the fauna of the Equatorial Atlantic. It may be that on reaching 

 the warm current from the Gulf of Guinea, passing to the south of 

 the Cape Verd Archipelago, we should find other forms. But what 



