Narrative of Bahama Expedition. 29 



midable spines, which would surely make themselves felt, upon 

 an^• attempt to swallow their possessors. 



The crustaceans were no less interesting as examples of 

 protective coloration than were the fishes. Sir Wyville 

 Thomson sa3's, " I know of no more perfect example of pro- 

 tective resemblance than is shown in the gulf weed fauna. 

 Animals drifting about on the surface of the sea with such 

 scanty cover as the single broken layer of the sea weed, must 

 be exposed to exceptional danger from the sharp-eyed oea 

 birds hovering above them, and from the hungr\' tishes search- 

 ing for prey beneath; but one and all of these creatures imi- 

 tate in such an extraordinary way, both in form and coloring, 

 their floating habitat, and consequenth' one another, that we 

 can well imagine their deceiving both the birds and the tishes."' 



These Crustacea, several of them, are characterized bv pure 

 white, not simply livid, markings, in sharp contrast to brown 

 blotches, thus resenibling the A)itc)iihi)-/iis. and the sea-weed, 

 with its growth of silvery white bryozoa. 



The following species of Crustacea were noted at this time: 

 Latreutcs ciisifcrus, Paheiucui iiafafor, JVcntti/oi^Tapsns iii/iiiifii>. 

 and A^cptiimis say/. A small barnacle of the genus Lepas 

 was found in great quantities on the sea weed. From the fact 

 that this species is quite conspicuous, it would seem that its 

 shell affords a sufficient protection against attack. 



A minute gasteropod moUusk was secured, but has not yet 

 been identified. The most abundant mollusk, however, was 

 a nudibranchiate {^Dendroiiotiis). which furnished still another 

 excellent example of protective coloration, resembling as it did 

 the sea weed, the Aiitcnuariiis, and the brachvuran JCautilo- 

 grapsiis. 



At that time and place but few birds were feeding on the 

 inhabitants of the sea weed, the only one at all abundant being 

 Wilson's petrel, a species of " mother Carey's chicken." 

 But the sargasso weed, in the course of its extensive travels, 

 passes through localities swarming with sea birds, which ren- 

 der the special protective coloration exhibited bv ito inhabit- 

 ants of vital importance. 



