DECAPODA 389 



Family CALLIANASSIDAE. 



With the characters j^iven above: about 7 American genera. 



1. Callianassa Leach. Cuticula soft and smooth; first 2 pairs of 

 periopods chehxtc, the first pair being large and very unequal in size; eye 

 stalks flattened; tiiird pair of maxillipeds flattened: about 20 species, 6 

 American. 



C. stimpsoni S. I. Smith. Length 6 cm.; ^^^^cv \^\c\ 



small cheliped about half as long as the large 



one; carapace smooth and glossy: from Long- 

 Island Sound southwards, in burrows in the 

 mud between tide lines and in shallow water. 



2. Gebia Leach. Cuticula soft and smooth ; Fig. 622 — Gehia affinis 



forward portion of cephalothorax compressed, 



with a triangular, hairy rostrum; second pair of periopods not chelate; 

 third pair of maxillipeds pediform: 10 species, 2 American. 



G. affinis Say (Fig. 622). Length 10 cm.: Long Island Sound to 

 South Carolina, living in burrows in the mud between tide lines and in 

 shallow water. 



Tribe 3. ASTACIDEA. 



Lobsters and crayfish (Sig. 623). Body of moderate or large size 

 and with a thick shell; first antennae w^th 2 flagella, second either with a 

 scale or with none and much longer than the first; no longitudinal 

 sutures, but usually a transverse cervical suture in the carapace: 4 

 families and about 150 species. 



Key to the families of Astacidea here described : 



tti Antennal scale and cheliped present. 



bi Animals marine 1. Nf.phropsidae 



62 Animals in fresh water 2> Astacidae 



Ca Antennal scale and cheliped absent 3. PALiNuraDAE 



Family 1. NEPHEOPSIDAE. 



Lobsters. Body of large size; rosti-um dentate along the lateral 

 margins; first 3 pairs of periopods chelate, the first pair very large, 

 forming the pinching claws: 3 genera.. 



HoMARUS Milne-Edwards. Rostrum with 3 teeth on each side; sec- 

 ond antennae with a small scale; eyes round: 2 species. 



H. americanus* M.-Ed. American lobster. Length up to 60 cm.; 

 greatest weight 13 kg. or over 28 pounds; length of the average adult 

 lobster 25 cm.; average weight less than a kg. or about one and three- 

 quarters or two pounds; color usually dark green with darker spots and 



* See "The American Lobster," etc., by F. H. Herrick, Bull. U. S. Fish. Com. for 

 1895. "Natural History of the American Lobster," by same. Bull. Bureau Fish., Vol. 

 29, p. 149, 1909. 



