170 MR. CYRIL CROSSLAND ON THE [Mar. 7, 



The following is the measurement of a female : — 



Height Length, Weight, 



at shoulder. ° '^ 



inches. inches. Ihs. 



25A 43i 36 4 teats. 



Habitat. As far as is known at present the range of this 

 Antelope is extremely limited. It is found on the upper water of 

 the Tana River, about 50 miles due south of Mount Kenya and 

 about 5 miles south-east of Fort Hall, where it is very plentiful. 

 It extends only about 10 miles down the Tana River, and is not 

 found further from the river than the Ithanga Hills and their 

 immediate neighbourhood. 



3. The Ecology and Deposits of the Gape Yerde Marine 

 Fauna. By Cyril Crossland, M.A., B.Sc, F.Z.S., 

 Carnegie Fellow and Fellow of the University of 

 St. Andrews. 



[Received January 13, 1905.J 



(Text-figures 21-26.) 



Contexts. 



Page 



1. Introduction 170 



2. Narrative and Results 172 



3. Comparison of the Fauna with that of East Africa... 176 



4. The Organic Deposits 178 



5. The St. Vincent Fringing- Reef 182 



6. Summary and Conclusions 185 



1. Introduction. 



An examination of the Collections made by me for Sir Charles 

 Eliot, K.C.M.G., in Zanzibar and East Africa in 1900-1902 

 showed at once that the whole Indo-Pacific Ocean from Afiica to 

 the Pacific Archipelagoes is one faunistic ai'ea. The region, 

 however, is not so well known as to admit of definite subdivision ; 

 in East Africa, e. g., we cannot say whether the numerous new 

 species discovered are characteristic of the region or mei-ely of the 

 special habitats which we examined. 



The wide distribution of many of the Opisthobranch Molluscs 

 is so striking as to have led Sir Chai-les Eliot to suggest an 

 expedition to the Tropical Atlantic, with the object of discovering 

 whether there is any relationship between the faunas of these so 

 widely separated oceans. As several species of Polych^eta also 

 appear to range from the Indo-Pacific to the Mediterranean and 

 even Caribbean Seas, the idea was highly attractive to me. I am 

 convinced, too, that the special difficulties of systematic work 

 on the Polychseta can be satisfactorily attacked only by the 



