27-i GENUS NIKA. 



similar character of the anterior feet, one being didactyle, 

 and the other monodactyle. In every other instance, how- 

 ever the feet forming a pair may differ in length, in size, 

 or in structure, they agree in the character of the terminal 

 portion, and are always both monodactyle or both didac- 

 tyle ; but in this genus one is invariably and distinctly 

 didactyle, while the other is as distinctly monodactyle. 



There are probably several species of this genus in the 

 Mediterranean, and I have in my possession two very dis- 

 tinct species found on our coast, one of which is undoubt- 

 edly Nika edulis of Risso, and the other an entirely new 

 species. 



