42 CAPE VERDE. 



schoolmaster, who had come to St. Vincent to join the 

 " Challenger," got lost on one of the mountains just before the 

 arrival of the ship, and died of exposure. His body was found 

 only after the lapse of several months. 



On a visit to Bird Rock, 1 found that the sea birds' dung 

 forms there, as at St. Paul's Rocks, pendent stalactite-like 

 masses. The rock is composed of volcanic conglomerate and 

 tuff, traversed in all directions by dikes of hard almost obsidian- 

 like lava. Small rock pools at a short distance above the 

 waves were filled with solid salt evaporated out from the spray. 

 On the main island, on the windward side, the shore rocks are 

 covered high up with an incrustation of salt dried out from the 

 spray blown up by the trade wind. Men-of-war use Bird Rock 

 occasionally as a target, and there were plenty of broken shot 

 and shell upon it. 



At low tide, along the shore of the main island, numerous 

 rock pools were exposed at low tide. These are inhabited by 

 vast numbers of sea urchins {Echiiioniefra), which rest within 

 rounded cavities in the rock excavated by the urchins for 

 themselves, both in the calcareous sand rock and volcanic 

 conglomerate. With these was a coral {Porifes), which forms 

 small rounded masses, bright yellow or whitish pink in colour, 

 and a grey Palythoa, a compound sea anemone, that is a 

 colony composed of sea anemones closely joined together, 

 and here forming sheet-like masses often a foot in diameter, 

 encrusting the rock. An Aplysia, or sea slug, with a pair of 

 large skin folds continued up from the sides of the body, and 

 lapping together over the back of the animal, was common, 

 and is probably the one referred to by Darwin, as seen at 

 St. Jago.* 



A Rock-crab {Grapsiis stri'gosus cf.) was very abundant, 

 running about all over the rocks, and making off into clefts on 

 one's approach. I was astonished at the keen and long sight 

 of this crab. I noticed some make off at full pace to their 

 hiding-places at the instant that my head showed above a rock 

 fifty yards distant. The crab often makes for the under side 

 of a ledge of rock when escaping from danger, and may then 

 be caught resting in fancied security by the hand brought 

 suddenly over it from above. The dry rocks were covered 

 with the dung of the crab, which is in the form of small brittle 

 white sticks about an inch in length, very puzzling objects at 

 first sight. The cast shells of the crab, which are bright red 

 and very conspicuous, were lying all over the rocks. 



At Still Bay, on the sandy beach of which, although it is on 

 the leeward side of the island and the sea surface was smooth, 



* Darwin, "Journal of Researches," p. 6, 



