DEC A POD A . ALP HE ADM. 



MACROURA. 



GENUS NIK A. Risso. 



PROCESSA. Leach, Latr. 



NIKA. Risso, Roux, Edwards. 



Generic Character. External antennce much longer than the 

 body, with the basal scale terminating in a single tooth at the 

 outer side; the inner margin hairy. Internal antenna termi- 

 nating in two filaments, the inner one the longer. External 

 pedipalps pediform, with four exserted joints, the second very 

 long, the terminal one pointed. First pair of legs dissimilar ; 

 that on the right side didactyle, that on the left monodactyle : 

 second pair more slender, very long, filiform, of unequal length ; 

 the arm and wrist multi-articulate, the hand minutely didactyle : 

 the remaining pairs very long, filiform, and monodactyle. Cara- 

 pace somewhat elongate, smooth, having a small, simple, com- 

 pressed rostrum. Abdomen a little bent at the third segment ; 

 the external laminae of the tail transversely divided near the 

 extremity. 



OF this interesting genus the only known specimen for 

 a long time was a small one on which Leach founded his 

 genus Processa, and which was found by Montagu on the 

 southern coast of Devon. Risso, however, had, a short 

 time before Leach's publication, given to the genus the 

 name of NiJca, of which Leach was not aware at the time. 

 Risso's name must, therefore, be retained, on the ground of 

 priority of publication. 



The remarkable peculiarity by which this genus is dis- 

 tinguished from every other form of crustacean, is the dis- 



T 



