1819.] NATURAL SCIENCES OF PHILADELPHIA. 411 



A single specimen was collected at Plantation Key, Fla., An- 

 tilles (Edw.), Key West (Gibbes), Isthmus of Panama (Streets). 



I give below a revision of the genera of Caridea belonging to 

 the families Crangonidse, Atyidse, and Palsemonidse. It is founded 

 on the arrangement of Dana. The genera of which I have seen 

 specimens I have designated by the letter " o." As I have recently 

 published a synonymieal list of the North American Shrimps (Bul- 

 letin Essex Institute, x. pp. 53-71, 1878), I have refrained in most 

 cases from giving the synonymy of the species collected by Prof. 

 Webster. 



CARIDEA. 



Body generally laterally compressed, the carapax not united to 

 the epistome, usually a broad lamelliform appendage (antennal 

 scale) on the basal joint of the antennae, sometimes, however, it 

 is wanting; antennulae bi- or tri-fiagellate ; mandibles varying in 

 form, sometimes with, sometimes without a palpus ; external max- 

 illipeds generally pediform ; feet generally long and slender ; gills 

 composed of lamellae, five to eight pairs ; abdomen long, the # sides 

 produced downwards. 



Family CRANGONIDiE. 



Mandibles slender, incurved, cutting edge narrow, not dilate or 

 bifid, without a palpus, first and second pairs of feet unequal. 



Sub-Family Crangoninae. 



First pair of feet stouter than the second. Hand sub-chelate, 

 the dactylus closing on the margin of the palm, the pollex being 

 spiniform. External maxillipeds pediform. 



Genus Crangon Fabr. 1 Rostrum very short, eyes free, anten- 

 nulae biflagellate, first pair of pereiopoda stout, but little longer 

 than the second, second pair slender, elongate, chelate, remaining 

 pairs acuminate. Branchiae five on each side. Type Crangon 

 vulgaris Fabr. 



Crangon vulgaris Fabr. Several specimens were collected at 

 Northampton Co., Ya. 



1 Including Steiracrangon Kinahan, Proc. Royal Irish Acad., viii. p. 08 

 (1862). 



