OBSERVA TIO.VS ON THE ASTACIDJi— FAXON. Gfi 1 



more strongly developed; the postorbital ridges bear distinct anterior 

 spines; the hand is broader and more hirsute, and the fingers are 

 tipped with more conspicuous, yellow, corneous nails. 



Length 38 mm. 



State of Guanajuato, Mexico, A. Duges (No. 16087, U.S.M.). 



CAMBARUS MONTEZUM/E AREOLATUS Faxon. 

 (Plate LXVI, fig. 2.) 

 Cambarus montezumce, var. areolata Faxon, Rev. Astacidse, Pt. 1, 1885, p. 123. 

 In this form the outline of the rostrum is similar to that of G. m. 

 dugesii, but the lateral margins are not .raised so as to form prominent 

 carinas. The lateral rostral spines and the spines at the anterior end 

 of the postorbital ridges are developed to about the same degree as 

 in G. m. dugesii. The characteristic feature of this form is the short- 

 ness of the posterior section of the carapace, which involves a very 

 short and broad areola. 



Parras, Coahuila, Mexico, Edward Palmer (No. 3650, Mus. Comp. 

 Zool.). 



CAMBARUS MONTEZUMA OCCIDENTALIS, new subspecies. 

 (Plate LXVI, figs. 3, 4.) 

 Cambarus montezumce Faxon (pars), Rev. Astacidaj, Pt. 1, 1885, p. 123. 



Kostrum plane above, margins but very slightly raised, tapering grad- 

 ually from the base to the tip without distinct lateral spines or defi- 

 nitely limited acumen. It reaches at the most to the distal end of the 

 second antennular segment. Postorbital ridges unarmed. 



Mazatlan, Mexico (No. 3652, Mus. Comp. Zool.). 



CAMBARUS CHAPALANUS, new species. 

 (Plate LXVII, figs. 1,2.) 



Similar to G. montezumce, but differs in the following regards: Borly 

 slenderer and more cylindrical; rostrum much longer and narrower, 

 reaching to the end of the antennular peduncle, somewhat hirsute, 

 armed with a pair of stout and sharp lateral spines, and a long spini- 

 form acumen; postorbital ridges terminating anteriorly in long and 

 strong spiniform teeth; antennal scales much longer and narrower and 

 armed with a much longer apical spine. 



Type. — Lake Chapala, State of Jalisco, Mexico, P. L. Jouy (No. 17698, 

 U.S.N.M.). One male. 



Same locality and collector (No. 16294, U.S.N.M.). Three males. 



The upper surface of the rostrum is plane, with raised lateral mar- 

 gins. The sides of the rostrum are convex, distinctly converging 

 before attaining to the lateral spines. The chelipeds and the male ■ 

 sexual organs are like those of the typical form of G. montezumce. 



