50 A REVISION OF THE ASTACIDA. 
the United States Exploring Expedition West of the Hundredth Meridian in 
pools east of the Canadian River. This locality, I presume is within the 
limits of the State of Texas. 
17. Cambarus Mexicanus. 
Astacus (Cambarus) Mexicanus, Exicuson, Arch. Naturgesch., XII. Jahrg., 1. 99, 1846. 
? Cambarus Aztecus, SsussuRB, Rev. et Mag. de Zool., 2° Sér., IX. 503, 1857. — Mém. Soe. Phys, Hist. Nat. 
Geneve, XIV. 460, Pl. III. fig. 23, 1858. 
Cambarus Mexicanus, Hacen, Il. Cat. Mus. Comp. Zodl., No. IIL. p. 84, 1870. (After Erichson.) 
Cambarus Mexicanus, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 141, 1884. 
Male. — Rostrum sub-plane, margins raised into crests gradually con- 
verging until within a short distance of the tip, where the crests become 
obsolete and the margins of the rostrum suddenly converge, without lateral 
spines, to form the short-pointed acumen. Post-orbital ridges parallel, obtuse 
in front. Carapace laterally compressed, of nearly equal width throughout, 
thickly punctate, sub-orbital angle rounded, cervical groove sinuate, no 
lateral spine, branchiostegian spine small, blunt; areola narrow, punctate. 
Abdomen as long and broad as the cephalothorax, telson with three or four 
small spines on each side, posterior segment short. Antennal scale broad, 
broadest in the middle. Chela long, subcylindrical, thickly beset with squa- 
mous ciliated granules; fingers about the same length as the hand, ciliate, 
granulate, costate. Carpus hardly sulcate above, covered with granules like 
the hand; no teeth on the inner margin. Meros granulate, outer surface 
smooth except on the margins and distal end; a biserial row of spines below. 
Third pair of legs hooked. Sternum setose. First pair of abdominal ap- 
pendages short, straight, a rectangular shoulder on the anterior margin near 
the tip, external and internal parts in close apposition to their tips; external 
part furnished with a small, slender, procurved, horny spine; internal part 
flattened with, apex straight, scarcely separated from external part. 
Length, 51 mm. Carapace, 25mm. Length of areola, 8 mm. ; width of 
areola, 0.6 mm. 
The above description is drawn up from a specimen in the Academy 
of Natural Sciences of Philadelphia, received from Mirador, Mexico, through 
Dr. Sartorius. The hooks on the third pair of legs are well developed, the 
first pair of abdominal appendages not articulated. I think there is no doubt 
that this specimen is Erichson’s C. Mexicanus, the types of which could not 
be found in the Berlin Museum either by Dr. Hagen or Von Martens. 
