194 



A HISTORY OF RECENT CRUSTACEA 



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

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



Fig. 16. — Ibacus ificisus (Peron) [Desmarest]. 



the head. Spence Bate enumerates twenty- two pairs of 

 branchias in this species. Why he changes Ihacus into 

 Ibaccus he has not bequeathed us any explanation. 



Pseudibacus Veranyi, Guerin, may receive a passing 

 mention, as a Mediterranean species. 



Ardus, 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 branchiae nineteen in number. 



In the definition of this genus Dana is practically fol- 

 lowing de Haan in stating that the palp of the third 

 maxillipeds is without a flagellum. 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. 



