OF ARTS AND SCIENCES. 129 



fingers costate, punctate and ciliate, outer margin of movable finger 

 furnished with low ciliate tubercles. Carpus broad, obliquely truncate, 

 punctate and ciliate above, with a median internal spine ; beneath, the 

 carpus has an acute median anterior and a small external spine. 

 Superior border of meros armed with two obliquely placed ante-apical 

 spines ; beneath ciliate ; of the outer row of biserial spines only the 

 distal spine is developed. Third segment of third pair of legs hooked. 

 First pair of abdominal appendages short, somewhat twisted, bifid 

 at apex ; rami short, thick, of nearly equal length, outer one sharp- 

 pointed, brown-horny, inner one curved outwards and then inwards, 

 flattened at apex. 



Length, GO mm. 



Male, form II. First abdominal appendages articulated near the 

 base, scarcely bifid, inner and outer parts thicker than in first form, 

 tips blunt, not brown-horny. 



Female. Annulus ventralis depressed, anterior wall not prominent, 

 posterior wall projecting backwards, a sinuous longitudinal fissure, 

 transverse fossa obliterated. 



Smoky Creek, Carter Co., Ky., and Oberlin, O. 



Very closely related to C. propinquus, but differs as follows : the 

 rostrum is never carinate, the chela is pubescent, the inferior median 

 anterior spine of the carpus is well developed ; the first abdominal ap- 

 pendages, though vei-y near those of C. projmiquus, have the apical 

 part shorter and less deeply bifid. These variations may perhaps be 

 deemed of varietal rather than of specific value ; but, aside from these 

 specimens, I have seen so little variation in the very large number of 

 C. propinquus examined, that I have decided to give the present form 

 a special name. 



I have examined many specimens, including the two forms of the 

 male, females, and young, collected by the late F. G. Sanborn in 

 Carter Co., Ky., and by Prof. B. F. Koons at Oberlin, O. 



Small individuals closely resemble young specimens of C propin- 

 quus, C. affinis, and more closely C. Putnami ; but the 3'oung of the 

 first may be distinguished by the carinated rostrum ; of the second, by 

 the longer rostral acumen, antennal scale, and anterior spine of post- 

 orbital ridge, by the longer hand and internal carpal spine, and by 

 the divergent tips of the first pair of abdominal appendages in the 

 male ; of the third, by the longer-spined antennal lamina, the long, 

 deeply-cleft abdominal appendages of the male, and the annulus 

 ventralis of the female, vvhich has a transverse fossa and bitubercu- 

 late anterior wall. 



VOL. XX. (n-. 8. XII.) 9 



