CAMBAEUS. 123 



In Archiv 1'iir Naturgeschichte, XXXVIII.. L872, page 130, Von ."Martens 

 communicates some remarks upon the form with lateral rostral spines, 

 received by the Berlin Museum from Puebla, Mexico, together with the 

 typical G. Moniezumce and C. Aztecus. This form he calls Gambarus Monie- 

 zumce, var. tridens. The largest part of those which 1 have myself seen, 

 amounting to about seventy specimens, have the lateral spines on the 

 rostrum, but in some specimens the spines are very small, and in others 

 reduced to a mere angle at the base of the acumen. 



Some of the female specimens collected hy Prof. A. Duges, in the col- 

 lections of the U. S. National Museum, have a short, broad, and hirsute 

 chela. 



Five imperfectly preserved dry specimens in the Museum of Comparative 

 Zoology come from Mazatlan. These specimens have a rather long, taper- 

 ing, entire rostrum, but do not differ from G. Moniezumce enough to warrant 

 separation. The sexual parts are the same as in the more eastern speci- 

 mens. It appears from these specimens that the genus Cambarus extends, 

 in Mexico, to the Pacific coast. 



There are also in this Museum six specimens, two males, form I., three 

 females, and one young male, collected by Mr. Edward Palmer near Parras, 

 Cohahuila, Mexico, which differ from G. Moniezumce, var. tridens, in having 

 the section of the carapace posterior to the cervical groove shorter, the 

 areola much broader. This form, which I have named provisionally (J. Mon- 

 iezumce, var. areolata, may prove to be a good species. But considering the 

 variability of individuals of C. Moniezumce, and the small number of Mexican 

 localities from which specimens have been received, I prefer to treat this 

 form as a variety simply, the more because the sexual parts of both male 

 and female are like those of C. Moniezumce. In this form, the distance from 

 the cervical groove to the posterior margin of the carapace is half (or even 

 less) the distance from the cervical groove to the lateral rostral spines. The 

 areola is about half as broad as it is long. Length of body, 28 mm. 



The largest specimen of G. Moniezumce which 1 have seen measures 

 38 mm. from tip of rostrum to end of the telson. 



Known Localities. — Mexico: marshes of the Valley of Mexico (Saus- 

 sure); ponds, Chapultepec; Lake Tezcoco,* near city of Mexico; Puebla 

 (Yon Martens); Lake San Roque, Trapuato (Coll. I'. S. .Nat. Mus.); Parras ; 

 Mazatlan. 



* Lake Tezcoco i> said to be salt. 



