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



Little previous woi'k on the marine fauna of the Islands has 

 heen clone ; indeed, it was diificult to get much information of 

 any sort about the locality * . The ' Challenger ' spent nineteen days 

 dredging in the harbour of St. Vincent with somewhat dis- 

 couraging results as regards the Polychseta and Opisthobranchiata. 

 The former appear to be unusually interesting, however, since, of 

 the foui-teen species collected, seven were new and obtained 

 nowhere else, while three v\^ere fovind to be widely distributed in 

 the North Atlantic and West Indies and others were Medi- 

 terranean t. 



The Canary Islands and Madeira have been Avorked by 

 Langerhans (Polychfeta) and other well-known zoologists. But 

 these Islands are well north of the Tropical zone and afford no 

 fair comparison with the Tropics of the Indian Ocean. 



2. Narrative and Results. 



In approaching St. Yincent t (text-fig. 22) one is immediately 

 sti'uck by the physical differences between the Cape Verde Islands 

 and the coast of East Africa. In place of the low level lines of 

 the local limestone formation, densely clothed with bush, or, at 

 Zanzibar, with cocoanuts, cloves, and mangoes, we ai-e here con- 

 fronted with the huge mass of the Island of St. Antonio, 7000 feet 

 in height, i-ising directly from the sea, with St. Vincent to the left, 

 lower (2400 feet) but even more ragged in outline. Both islands 

 show their volcanic origin very obviously, and their grey precipices 

 and red slopes are utterly devoid of vegetation. The shores 

 themselves, with which we are more dii-ectly concerned, also 

 differ. In place of the broad shore-platform, smooth, barren, and 

 almost quite devoid of loose stones, which is characteristic of the 

 East- African coral-rock, we have here a shore, so narrow as to be 

 almost invisible on the Admiralty Chai-ts, composed of lava, and 

 often covered with stones of all sizes, from that of a cottage 

 downwards. 



The tides rise from 3 to 5 feet at springs, according to the 

 locality, as against 8 to 12 feet in East Africa. In partial 

 correspondence with this the rich zone of the shore in the latter 

 locality is from lowest tide-level down to 2 or 3 fathoms, so that, 

 without wading, little could be done. Here also there is a well- 

 marked rich zone, but it extends halfway up to high- water mark 

 and ends abruptly 2 or 3 feet below the level of lowest springs. 

 The rocks of this zone are covered by a belt of mossy green, 

 brown, and red seaweeds and nullipores ; below it they are bare 

 or only merely painted over by nullipore and bear little else 



* The most useful accounts are in the ' Universal Geography,' vols. xi. & xii., and 

 the Admiralty Pilot Series. 



f ' Challenger ' Eeports, Summary of Eesults, vol. i. pp. 303-314. The avian fauna 

 has been collected for the British Museum by Captain Boyd Alexander, whose 

 results are recorded in the ' Ibis,' 1898, pp. 74^118 and 277-285. 



J Properly the Island is San Vicente, the town Mindello, and the Harbour Porto 

 Grande. For simplicity I use St. Vincent for all three. 



