ST. JAGO, CAPE VERDE ISLANDS. 



61 



nippers have slender arms of equal length and dimensions, 

 which are linked together so as to open and shut like a pair of 

 forceps, closing flat against one another. 



atya sulcatipes. (Xatural size.) 



a One of the front pairs of walking legs. Beneath ; the same pair enlarged ; a the nippers 



widely open ; b the crescent-shaped joint to which they are hinged. 



At their extremities these forceps arms are provided with 

 thickly-set brushes of long hairs, as long as the arms themselves. 

 These hairs expand in the water when the forceps are opened, 

 and evidently form a widely-sweeping grasping surface, by 

 which small particles of food or minute animals can be caught. 

 No doubt these forceps catch the food of the Atya, and the 

 larger legs with simple pointed ends enable it to hold on to the 

 stones in the rapid stream. 



The pair of forceps is not attached directly at its hinge 

 joint to the end of the limb, but at a point on the side of one of 

 the arms. Here it is hinged on to a crescent-shaped joint, into 

 the crescent of which the rounded end of the forceps is received 

 when the apparatus is retracted and at rest. The complicated 

 manner of jointing gives a very wide sweep and great mobility 

 to these very curious prehensile organs. 



The genus Atya must, from its very wide distribution, be a 

 very ancient one. Species of the genus occur in the West 

 Indies, in the Philippines, in Samoa, and in Mexico, besides in 

 the Cape Yerde Islands. The Cape Yerde species * is possibly 



* Atya sulcatipes (Newport) ? A. scabra (Leach). " Ann. and Mag. 

 Nat. Hist.," 1847, p. 158, where is a list of species. Upolu is in it placed by 



