190 CLASS CRUSTACEA. 



Pen^us, Fah.^ 



In which no articulation of the feet presents any annular 

 division ; their mandible-palpi are raised and foliaceous. 

 We see a small appendage, in the form of an elliptical plate, 

 at the base of the feet, a character which seems to approach 

 these Crustacea to pasiphae, the last subgenus of this section, 

 and to those of the following, (Palcejuo)} sidcafus, Oliv.) 



Other penaei have the intermediate antenna? terminated by 

 long threads ; these are those of our second division. {Fenaus 

 monodon, Fab.) 



Stenopus, Latr., 



Are distinguished from the last by the transverse and annular 

 divisions of the two articulations before the last; of the four 

 posterior feet ; all the body is soft ; the antennae and feet are 

 long and slender; those of the third pair are the broadest. 

 {Cancer setiferiis, Linn.) 



The other Carides, many of which have the intermediate 

 antennae terminated by three threads, present at most but 

 two pair of didactylous claws, formed by the four anterior 

 feet. 



A subgenus established on a single species proper to North 

 America, that of 



Atya, Leach, 



Is removed from all the analogous Crustacea, by an anomalous 

 character; the forceps terminating the four claws is cleft as 

 far as its base, or appears to be composed of two lingers in 

 the form of lashes, united at their origin ; the articulation 

 which precedes, is in the form of a crescent; the second pair is 

 the largest ; the middle antennae have but two threads. {Atya 

 scahra, Leach.) 



In all the following subgenera, the fingers of the forceps 

 arise only at a certain distance from the origin of the last 



