48 A EE VISION OF THE ASTACID.E. 



C. Carolimis, and C. gracilis resemble C. Diogenes of Group III. in the general 

 form of body, linear areola, small antennal scale, broad chela, etc. The fore 

 border of the carapace is augulated behind the antennas in C. simulans, 

 C. Mcxicamus, C. Citbensis, and C. gracilis ; not angulated in C. advena and 

 C. Curolliius. The rostrum is armed with small lateral teeth in C. Cubcnsis ; 

 in the other species of this group the rostrum has no lateral teeth. 



Of the species belonging to this group, Hagen knew only C. advena and 

 C. Carolimis. These were placed by him, as aberrant forms, in Group III. 

 (C. Barton! i). 



liostrum with small lateral teeth, areola broad. C. Cubensis. 



Areola of moderate width. Chelae subeylindrical. C. Mexicanus. 

 Areola narrow. Auteimal scale large and broad. C. 



Rostrum without lateral teeth. Fi . ol]t mMgin of carapace angnlated 



behind antenna-. C. gracilis. 

 Areola linear, or obliterated m the middle. 



1 Front margin of carapace uot augu- 

 *- lated. C. advena, C. Carolinus. 



16. Cambarus simulans. 



Plate I, fig. 3, Plate VIII, tigs. 3, 3', 3 a, S a'. 



Ciiui/inr/i.1 siiii/ifans, FAXON, Proc. Ainer. Acad. Arts and Sei., XX. 112, 1S84. 



Male, form I. Rostrum broad, deeply excavated ; margins raised into 

 sharp crests, which overhang the base of the sides of the rostrum, converging, 

 sinuated before the tip to form the short acumen; no lateral spines; the 

 acumen is barely margined. Post-orbital ridges subacute in front, divergent 

 and ending in slight callosities behind. Carapace ovate, narrowing in front, 

 gastric area smooth, cardiac area lightly punctate, sides granulate ; anterior 

 border notched behind the antennas ; cervical groove sinuate, split on the 

 sides, with a minute terminal branchiostegian spine; no lateral spine; areola 

 more than one half as long as the distance from the point of the rostrum to 

 cervical groove, narrow, carinate, expanding into an anterior and a posterior 

 triangular Held; two longitudinal dotted lines run along the areola from the 

 .interior triangle to the posterior triangle, which is irregularly and sparsely 

 dotted. Abdomen broad, shorter than carapace, punctate, posterior margins 

 !' pleura obliquely convex; hind margin of anterior segment of telson bi- to 

 multi-deiiliriilate on each side, posterior segment short, hind border almost 

 straight; median rib of inner plate of swimmeret ends inside of the mar- 

 gin. I5asal segment of antennule with a spine below. Antenna? shorter than 



