CAMBARUS. 25 



of epistoma broadly triangular. Antennae shorter than the body. Antennal 

 scale a little shorter than the peduncle, equal to the rostrum, broad, broadest 

 at the middle. Chelipeds slender, chela long, inner and outer margins par- 

 allel, squamoso-tuberculate, tubercles ciliate, those along the inner margin of 

 the hand blunt spiniform. Fingers longer than the hand. Opposed margins 

 of lingers ciliate, with one or two small spinous teeth. Carpus long triangu- 

 lar, smooth without, tuberculate and spinous within. Meros with scattered 

 impressed dots without, tuberculate on the upper margin ; one or two spines 

 at the anterior end of upper margin, two rows of spines beneath. Third and 

 fourth pairs of legs hooked on third segment. Anterior abdominal legs of 

 moderate length, deeply excavated on the outer side near the tip; a beard- 

 like tuft of cilia from the protuberance behind the excavation ; the tip bears 

 three flattened horny teeth ; inner part ciliate, with a long spine directed 

 outwards and forwards. 



The second form of the male has shorter chelipeds, smaller hooks on the 

 second and third pairs of legs, the terminal teeth of the first pair of ab- 

 dominal legs smaller and not corneous. 



In the female the chelipeds are short, the chela? broad. Sternum bitu- 

 berculate between the fourth pair of legs. Annulus ventralis umbilicoid, 

 with a tubercle in the median depression. 



Length, 100 mm. Rostrum, 15 mm. ; acumen, 3 mm. Length of cara- 

 pace, 51 mm. From cervical groove to posterior margin of carapace, 18.5 

 mm. Abdomen, 50 mm. Width of areola, 1.5 mm. Chelipeds, 92 mm. 

 Chela, 43 mm. 



Known Localities. — Mississippi : Macon, Artesia. 



Closely related to Cambarus Blandingii, but easily distinguished by the 

 first pair of abdominal legs of the male, which are characteristic even in very 

 small specimens. Over a dozen specimens of this species (including males 

 of tin; first form, males of the second form with first pair of abdominal 

 appendages articulated near the base, and unarticulated, and females) were 

 collected by Prof. 0. P. Hay in Eastern Mississippi. One lot has a particular 

 locality specified, — Macon. Macon is situated on the Noxubee, an affluent 

 of the Tombigbee River. Another lot was collected at Artesia, a town about 

 twenty mil.s north of Macon. 



