CAMBARUS. 83 



typical form of C. pettucidus, resembling in this respect the form C. pellucidus 

 im rmis. The terminal segment of the telson narrows ut the hinder end more 

 than in C. pellucidus. I do not find the differences in the mandibles, antenna! 

 scales, and chelae mentioned by Packard. 



33. Cambarus Jordani. 



Plate III. fig. 3. 



Cambarus Jordani, Faxon, Proo. Amer. Acad. Arts and Sci., XX. 119, 1SS4. 



Male, form II. — Rostrum broad, subplane, sides nearly parallel, acumen 

 long, with minute lateral teeth at base. Post-orbital ridges provided with 

 sharp anterior spines. Carapace punctate (sparsely so on the gastric region), 

 slightly granulated on the sides. A single acute spine on each side of the 

 carapace behind the cervical groove, and a branchiostegian spine on the 

 anterior border. Sub-orbital angle prominent. Areola long, narrow, widen- 

 ing gradually anteriorly, suddenly posteriorly, smooth, with but few puncta 

 irregularly disposed in its field. Abdomen longer than the cephalothorax ; 

 proximal segment of the telson bispinous, distal segment rounded posteriorly. 

 Epistoma triangular. Antennte equal in length to the body minus the telson. 

 scale broad, greatest width toward the distal end, which is sub-truncate 

 and furnished with a sharp external spine. Third pair of maxillipeds hairy 

 within. Chela punctate, ciliate ; inner margin of hand short, serrate ; 

 fingers long, costate, outer border of movable one serrato-tuberculate. Car- 

 pus with a strong, acute median spine, and a small basal spine on inner 

 border; a small spine at each articulation with the chela. Meros smooth 

 on the external surface, two ante-apical spines obliquely placed on the upper 

 edge. First pair of abdominal appendages short, thick, articulated near the 

 base, terminating in two blunt, recurved teeth. 



Length of bod)-, 47 mm. ; of carapace, 23 mm. ; of abdomen, 24 mm. ; 

 of rostrum, G mm.; of acumen of rostrum, 2 mm. From point of rostrum 

 to cervical groove, 15 mm. ; from cervical groove to hind margin of cara- 

 pace, 8 mm. Width of areola, 1.3 mm. Length of antenna}, 44 mm. 



Of this species I have seen but one specimen, a male of the second form, 

 collected by Prof. D. S. Jordan in the Etowah River near Rome. Georgia, 

 communicated by Mr. P. R. Uhler, of Baltimore. It has a toothed rostrum 

 and first abdominal appendages like C. Bartonii. It is distinguished from 

 the other allied species by its ilat rostrum and narrow areola. 



