DECAPODA 



391 



Fig. 624 The anterior abdominal appendage 

 (male) in Cambarus (Ortmann). A, O. pro- 

 pinquus; B, C. Umosus; C, C. bartoni; D, 

 C. diogenes. 



No gills on the last thoracic somite and 17 pairs in all; first pair of 

 swimmerets bifid and often hooked at the apex in the male: about 70 

 species, all in North America 

 and east of the Rocky Moun- 

 tains. The animals live in 

 streams, lakes, and swamps, 

 resting under stones or in 

 burrows or among aquatic 



vegetation near the surface; A g C 



a few species are terrestrial, 

 living in burrows. Crayfishes 

 are omnivorous feeders, eat- 

 ing decaying animal and plant substances, but also living animals and 

 plants. Spawning occurs in the springtime and pairing in the fall in the 



case of C. diogenes and C. Umosus 

 and others, but C. bartoni and others 

 probably pair and spawn the year 

 round. The eggs are carried by the 

 mother attached to her abdominal 

 legs until they hatch; the young ani- 

 mals when born have the form of the 

 parents and live for a while with the 

 mother, holding on to her abdominal 

 legs with their claws. Crayfishes are 

 used for food in New York and other 

 large cities. 



C. bartoni* (Fabricius) (Fig. 624, 

 C). First pair of abdominal append- 

 ages of the male terminated with 2 

 strongly recurved tips; length 8 cm.; 

 the eastern specimens have a short 

 quadrangular rostrum; in the western 

 specimens the rostrum tends to be 

 elongate; body with few or no hairs; 

 carapace depressed: North America, 

 almost to the Mississippi, but espe- 

 cially along the Atlantic slope, usu- 

 ally in clear, small streams, but also 



occasionally in muddy ones where it may burrow; one of our most 

 widely distributed and commonest crayfish. 



Fig. 625 Cambarus pellucidus 

 (Kingsley). 1, first antenna; 2, 

 second antenna ; 3, antennal scale ; 

 4, periopods ; 5, carapace ; 6, abdo- 

 men ; 7, uropod ; 8, telson ; 9, rostrum. 



* See "Notes on the Habits of Certain Crayfish," by C. C. Abbott, Am. Nat, Vol. 

 7, p. 80, 1873. 



