194 



A HISTOEY OF EECENT CRUSTACEA 



others of this family, the basal joint of the second antennas 

 is not free, but closely fused with the ventral portion of 



FIG. 16. Ibacus incisus (Peron) [Destnarest]. 



the head. Spence Bate enumerates twenty-two pairs of 

 branchias in this species. Why he changes Ibacus into 

 2baccas he has not bequeathed us any explanation. 



Pseudibacus Vemnyi, Guerin, may receive a passing 

 mention, as a Mediterranean species. 



Arctus, Dana, 1852, has the rostrum very short and 

 truncate, the second antennae remote from one another, 

 the exopod of the third maxillipeds without a lash, and the 

 pairs of branchias nineteen in number. 



In the definition of tin's genus Dana is practically fol- 

 lowing de Haan in stating that the palp of the third 

 maxillipeds is without a flageilum. Mr. Spence Bate 

 translates this into his own terminology, and speaks of the 

 genus ' having no ecphysis attached to the second pair of 

 gnathopoda,' which would mean that there was no exopod 

 to the third maxillipeds at all. But that is not the case. 



