108 A REVISION OF THE ASTACIDA. 
Female. — Hand small, fingers not gaping, ciliated within; sternum 
between fourth pair of legs plane; annulus ventralis bilaterally symmetrical, 
anterior border bituberculate, posterior border unituberculate, transverse 
fossa deep, recurved at each end. 
Measurements of male, form I.— Length of body, 49 mm. Length of 
carapace, 25mm. Length of rostrum, 6 mm. Length from end of rostrum 
to cervical groove, 15.6 mm. Length from cervical groove to hind border 
of carapace, 9.5 mm. Width of areola, 2 mm. Length of abdomen, 25 mm. 
Length of chela, 23.5 mm. Length of internal margin of hand, 9.5 mm. 
Breadth of chela, 11.6 mm. Length of movable finger, 14 mm. 
Two specimens, first form of male and female, in the Museum of Compar- 
ative Zodlogy, from Irondale, Mo. 
This species has the general form of body, rostrum, and chelz of the 
C. Bartoni group, together with the male abdominal appendages of the 
C. affinis group. These appendages have a projecting shoulder at the base 
of the rami, on the anterior edge, as in C. rusticus, C. Putnami, ete.  C. wi 
mums and C. Mississippensis, belonging to the C. afinis group, also have the 
rostrum devoid of lateral spines, but in eeneral habit of body they do not 
resemble C. Barton and its allies, as is the case with the present species. 
47. Cambarus rusticus. 
Plate IX. figs. 8, 8’, 8a, 8a’ (first abdominal appendages of male). 
Cambarus rusticus, GiRARD, Proc. Acad. Nat. Sci. Phila., VI. 88, 1852. 
Cambarus rusticus, Hacen, Ill. Cat. Mus. Comp. Zool., No. IIL. p. 71, Pl. I. figs. 80-83, Pl. III. fig. 161, 
1870. 
Cambarus placidus, HaGEN, op. cit., p. 65, Pl. I. figs. 76-79, Pl. IIT. fig. 158, 1870. 
Cambarus juvenilis, HAGEN, op. cit. p. 66, Pl. I. figs. 29-33, Pl. IIT. fig. 157, 1870. 
1 
Cambarus rusticus, SMitu, Rep. U. 8. Comm. Fish and Fisheries for 1872 and 1873, p. 689, 1874. (After 
Hagen. No description.) 
Cambarus placidus, SMiru, op. cit.. p. 638, 1874. (After Hagen. No description.) 
Cambarus juvenilis, SMITH, op. cit., p. 88, 1874. (After Hagen. No description.) 
Cambarus Wisconsinensis, Buxvy, Bull Il. Mus. Nat. Hist., No. I. p. 4, 1876. — Trans. Wis. Acad. Sci., V. 
181, 1882. — Geol Wis., Surv. 1873-1879, I. 402, 1883. 
Cambarus placidus, Forsrs, Bull. Il. Mus. Nat. Hist., No. I. pp. 4, 19, 1876. (After Hagen.) 
Cambarus Wisconsinensis, Forsus, op. cit., p. 19. (After Bundy.) 
Cambarus rusticus, Bundy, Trans. Wis. Acad. Sci., V. 181, 1882.— Geol. Wis., Surv. 1878-1879, I. 402, 
1883. (Not described.) 
Cambarus placidus, Bunny, Traus. Wis. Acad. Sci., V. 181, 1882. (Not described.) 
Cambarus rusticus, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 148, 1884. 
Male, form I. — Rostrum long, narrow, concave on the sides, excavated, 
margins thickened, dotted-lined, divergent at the base ; acumen of moderate 
