141 



than the rostrum, broad, broadest at the middle, subtruncate at the end, 

 with an external apical spine. Third raaxillipeds densely setose within and 

 below. Anterior process of the epistoma with very convex sides. Chela 

 broad, flattened above, punctate, external border marginate; inner margin 

 of the hand short, with a double row of dentiform tubercles; fingers long, 

 movable one tuberculate on the external border, toothed on the internal 

 border ; external finger flat above, internal margin toothed, and bearded at 

 the base. Carpus armed with a row of small tubercles on the upper side, 

 with a strong and acute internal median spine and a small one at the base ; 

 on the lower side the carpus is provided with a prominent median spine and 

 an external one at the point of articulation with the chela; in some specimens 

 there is a small spine on the lower face of the carpus, between the median 

 spine and the large one on the internal margin. Third pair of legs armed 

 with a hooped tubercle on the inner margin of the third segment. First 

 pair of abdominal appendages of moderate length, twisted, deeply bifid, 

 very broad in the middle; rami slender, styliform, strongly recurved, the 

 inner one a little shorter and more curved than the outer one, the outer 

 one corneous. Length from tip of the rostrum to the end of the telson. 

 61 mm. Length of antennae, 67 mm. 



The second form of the male differs from the first form in having smaller 

 chelae, the tubercles on the third pair of legs less developed, the first ab- 

 dominal appendages less deeply cleft, the rami stouter, blunter, and not 

 corneous. 



In the female the chela is similar to that of the second form of the male, 

 the sternum between the fourth pair of legs is smooth, the annulus ven- 

 tralis triangular with a median longitudinal fissure. 



Labette Co.; W. S. Newlon. 5 males form I., 5 males form II., 7 fe- 

 males. 



This species much resembles O. virilis, especially the form called variety 

 A by Dr. Hagen. It differs in the shape of the first abdominal append- 

 ages of the male. In (7. JV'm the rami of these appendages are shorter and 

 more strongly curved than in C. virilis, but not so much recurved as in C. 

 immunis. The areola is narrower than in (\ vh'ili*. The first abdominal 

 appendages are very like chose of C. Palmer i, as far as can be seen by a 

 comparison of the second-form males alone ; but the areola is not obliter- 

 ated in any part of irs course in C. Nais and the rostrum is more tapering 

 than in C. Palmm'. 



6. r:niil:irns virilis Hagcn. 111. Cat. MuS. Comp. Zool., No. Ill p. 



63, PI. I. figs. 23-28, PI. II. figs. 128-132, PI. III. fig. 155, PI. VIII., 

 1870. Camluni* ,1,-hilu Bundy, Bull. 111. Mus. Nat. Hist. No. I. p. 24, 

 1876. Trans. Wis. Acad. Sci. V. 181, 1882. Geol. Wis. Surv. 1873-79, 

 I. 403, 1883. Camlani* cnu^l Streets, Bull. II. S. Geol. Geogr. Surv. 

 Terr., III. 803, 1877. 



Tributary of Kansas River, Shawnee Co. F. W. Cragin. Ward's 

 Creek, Shawnee Co. J. B. Fields and F. W. Cragin. Wabaunsee Co. J. 

 B. Fields. Garden City, F. W. Cragin. Leavenworth (Coll. Acad. Nat. 

 Sci. Phila.) Manhattan, (Coll. Acad. Nat. Sci. Phila.) Republican River, 

 northwest of Fort Riley (Coll. Acad. Nat, Sci. Phila.) Ellis, (Coll. Pea- 

 body Acad. Sci. Salem.)* 



