DECAPODA. CRANOONIDM. 



MACROURA. 



GENUS CRANGON. 



AsTACus. Herbst, Penn. 



Crangon. Fabr. Latr. Leach, Edw. 



Generic Character. — External antennce situated nearly on the 

 same line with the internal, on the outer side, and a very little 

 beneath them. Internal antennas dilated at the base, and having 

 at the outer side a broad scale ; the peduncle short, and termi- 

 nating in two filaments. Extei-nal jjedipalps pediform ; the ter- 

 minal joint obtuse and flattened. First pair of feet subdidactyle, 

 stronger and thicker than the others ; the hand flattened, the 

 moveable finger inflexed upon the hand, and meeting a rudi- 

 mentary thumb : the second and third pairs very slender ; the 

 second didactyle ; the fourth and fifth shorter and thicker than the 

 former. Carapace depressed, and with only a rudim-ent of a ros- 

 trum. Abdomen large and rounded. Branchice only seven on 

 each side. 



The family to which this species belongs is distinguished 

 from all others by the insertion of the two pairs of an- 

 tennae on the same line, and the subcheliform structure of 

 the anterior hand. I am inclined to follow Dr. Milne- 

 Edwards in restoring to this genus Leach's genus Ponot- 

 pliilus and Risso''s Egeon, separated unnecessarily from 

 Crangon, which, in fact, constitutes the only known genus 

 of the family. It may, however, be conveniently divided 

 into two sections, in one of which the second pair of feet is 

 as long as the first, in the other it is not much more than 

 half as long. The first constitutes the genus Crangon of 

 Leach ; the second Pouto^hihis of the same author. 



