124 Natural History Bulletin. 



on the basal part of the hand fit exactly into those on the 

 meros, while the spines of the internal superior edge of the 

 distal portion of the hands fit between similar spines on the 

 anterior margin of the thorax, thus completely disguising the 

 shape of the animal so that no one would think it a crab at alL 



Among the Cancroidea, a minute species of Panopats mav 

 be noted. One of the commonest and most conspicuously 

 marked forms is Lcptodiiis jioridamis (Gibbes), with its pol- 

 ished iyory-black chelae terminating in white tips. Pliryino- 

 diiis iiiaciilafits Stimpson bears considerable superficial resem- 

 blance to the last, but the chelae are not so deep a black., 

 shadinjr distally into brown and then white. ^Ic/a-a sct/'arra 

 Stimpson is another species haying black chela?. This char- 

 acter occurring among so man}- genera living in the same 

 locality seems to indicate some peculiar utility in this conspic- 

 uous marking. These animals liye in shallow water, crawling 

 among the alga?, corals, gorgonians, etc. A large number, 

 perhaps all of them, are protectiyely colored in the main, or 

 have the habit of covering themselves with sand, bits of shelL 

 or even with living alga? and other organisms. The chela? 

 and e3'es are almost the only portions of the body not protec- 

 tively colored or covered. Any conspicuous marks generally 

 classed under the head of "attractive coloration."' for the 

 purpose of attracting other individuals of the same species but 

 of opposite sex, must therefore be placed on the chehv in 

 order to serve their purpose. Such conspicuous markings do 

 not interfere with the effectiveness of general protective col- 

 oration, because the chela^ are stowed away under the cara- 

 pace so as to be completely concealed when not in use. 



Lionicra loiigiiuana A. M. E. has a comparatively smooth 

 carapace with short, black fingers, and a long hand which is 

 colored a rich brown, with distinct pits dotted over its surface.. 

 Among the most abundant and interesting crabs is j\cptuiiiis 

 spinicarpus Stimpson, which has a verv long, slender, spine 

 projecting forward from the distal end of the carpal joint, and 

 extending beyond the base of the fingers. This spine is 

 furnished with a close-set row of hairs or cilia on the side 



