660 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xx. 



the greater length of the section of the carapace behind the cervical 

 groove, and its shorter, more tapering, and carinated rostrum. All of 

 these characters, with the exception of the carination of the rostrum, 

 also serve to separate G.propinguus sanbornii from the present species. 

 The habitat of G. erichsonianus, eastern Tennessee and northern 

 Alabama, is closely adjacent to that of G. spinosus. G. propinquus is a 

 more northern form, unknown south of the Ohio. C. propinqims 

 sanbornii has been found in Kentucky and Ohio. 



CAMBARUS FORCEPS Faxon. 



Clinch River at Walker's Ford, eleven miles northwest of Tazewell, 

 Tennessee; Bull's (or Big Sycamore) Creek, tributary of Clinch River, 

 seven miles south of Tazewell, Tennessee. (Coll.U.S.N.M.) 



GROUP V. (Type, Cambarus montezumw Saussure.) 



Third segment of second and third pairs of legs of male hooked. 

 First abdominal appendages similar to those of Group IV. 



CAMBARUS MONTEZUMA Saussure. 



The typical form of C. montezumw comes from the plain of the City 

 of Mexico. It has also been recorded from Puebla 1 and from Vera 

 Cruz. 2 The Puebla specimens (var. tridens von Martens) are described 

 as having a pair of small lateral teeth near the apex of the rostrum, 

 but this is also true of many of the specimens, especially the second 

 form males and the females, from the type locality. In the typical form 

 the rostrum is smooth and lightly hollowed out above, the sides of the 

 rostrum are nearly parallel (but slightly convex) from the base to the 

 proximal end of the acumen, which is short (not surpassing the second 

 antennular segment) and flanked by very small lateral teeth (often 

 obsolete). The postorbital ridges are unarmed, or furnished at the most 

 with the merest vestige of the anterior spines. The portion of the 

 carapace posterior to the cervical groove is much more than half the 

 distance from the groove to the anterior extremity of the rostrum. 



CAMBARUS MONTEZUMiE DUGESII, new subspecies. 



(Plate LXVI, fig. 1. ) 



Cambarus montezumce Faxon, Proc. U. S. Nat. Mus., XII, 1889, p. 633. 



Differs from G. montezumw as follows: The upper surface of the 

 rostrum is perfectly flat, except for the margins, which are raised so as 

 to form lateral carinas; the sides of the rostrum converge from the 

 base to the proximal end of the acumen, which is slenderer and a little 

 longer than in G. montezumw; the lateral teeth of the rostrum are 



1 Von Martens, Arch. f. Naturgesck., 38ter Jahrg., 1872, I, p. 130. 

 2 Ortmann, Zoolog. Jahrb., Abth. f. Syst., VI, 1891, p. 12. 



