CAMBARUS. 81 



beneath. Third joint of tliird pair of legs hooked. Fourtli pair of legs with 

 a conical tubercle on the first segment. First pair of abdominal appendages 

 short, stout, twisted, distal half bent in towards the median line of the body ; 

 internal part truncate at apex, with a small spine directed backward and 

 outward; external part longer, ending in a short, recurved, blunt, laterally 

 compressed, horny tooth. 



Measurements. — Length of body, 81 mm.; of cephalothorax, 43.5 mm.; 

 of abdomen, 37.5 mm. From tip of rostrum to cervical groove, 27 mm. ; 

 from cervical groove to posterior border of carapace, 16 mm. Length of 

 rostrum, 11 mm.; of acumen of rostrum, 5 mm.; of antenna?, 91 mm.; of 

 chela, 36 mm. ; of movable finger, 22 mm. Width of base of acumen of ros- 

 trum, 3 mm.; of areola, 3 mm. ; of chela, 15 mm. 



One specimen, collected by Mr. F. W. Putnam in Green Eiver, near the 

 Mammoth Cave, Ky., November 3, 1874. 



This species is very distinct from every other known crayfish. In its 

 general appearance it approaches those species included in the group typi- 

 fied by C. Bai'tonii. The rostrum, however, is more after the fashion of C. riis- 

 ticus, but the lateral spines are much larger and stand erect. The impressed 

 external finger recalls C. BaHonii, var. robusta. The sexual appendages are 

 formed nearly as in C. Bartomi The development of the antennae is extraor- 

 dinary. 



32. Cambarus hamulatus. 



riate IV. fig. G, Plate IX. flgs. 1 a, 1 a'. 



Orconectes hamulatus, Cope and Packard, Amcr. Naturalist, XV. 8S1, PI. YII. figs. 1, \a, \b, Nov. 18S1. 

 Cambarus hamulatus, Faxon, Proc. Ainei'. Acad. Arts and Sci., XX. Ii5, 1881. 



Male, form II. — Rostrum long, subexcavated, foveolate at base, mar- 

 gins moderately raised, converging, lateral spines strong and acute ; acumen 

 long, narrow, acute. Post-orbital ridges slightly developed, impressed with- 

 out ; with prominent acute anterior spines. Carapace subcylindrical, flattened 

 above, region posterior to cervical groove long ; smooth above, granulated 

 on the sides. A sharp spine on each side at the base of the antenna? at the 

 anterior extremity of the cervical groove, and two or three on each branchial 

 region just behind the cervical groove, one of which is prominent, the other 

 minute. Areola of moderate width, sparsely punctate, sides parallel. Abdo- 

 men longer than the cephalothorax, equal to the cephalothorax in width. 



11 



