CAMBARUS. 99 
41. Cambarus immunis, 
Plate X. figs. 6a, 6a’ (first abdominal appendages of male, form II.). 
Cambarus immunis, Hacen, Ul. Cat. Mus. Comp. Zodl., No. IIL. p. 71, Pl. L figs. 101, 102, Pl. IT. fig. 160, 
Pl. VIII. fig. b, 1870. (Male, form I., and female.) 
Cambarus immunis, Smiru, Rep. U. S. Comm. Fish and Fisheries for 1872 and 1873, p- 639, 1874. (After 
Hagen. No description.) 
Cambarus immunis, Forses, Bull. Il. Mus. Nat. Hist., No. I. pp. 4, 19, 1876. (Male, form II., and young.) 
Jambarus imnmunis, Bunxpy, Proe. Acad. Nat. Sci. Phila., 1877, p.171. 
Cambarus siguifer, Herrick, Tenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., for the Year 1881, p. 253, 1882. 
Cambarus immunis, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 146, 1884. 
Known Localities. —New York (Coll. L. A. Lee). Indiana: White River 
(Coll. Bost. Soc. Nat. Hist.); Fall Creek, Indianapolis (Coll. Peabody Acad. 
Sci.) ; Long Lake, Kendallville (Bundy). Hlinois: Aux Plains (Coll. U.S. Nat. 
Mus.); Belleville ; Lawn Ridge; Normal; Oquawka (Coll. O. P. Hay). Michi- 
gan: Detroit River, Detroit. Wisconsin: Milwaukee (Coll. U. S. Nat. Mus.). 
Minnesota: Richfield, Hennepin Co, Iowa: West Liberty. Missouri: St. 
Louis (Coll. P. R. Uhler). Kansas: Leavenworth (Coll. Acad. Nat. Sci. Phila.) ; 
Ellis (Coll. C. H. Gilbert). Wyoming: near Laramie (Coll. U.S. Nat. Mus.). 
Alabama: Huntsville. Mexico: Orizaba (Coll. U.S. Nat. Mus.). seeg. 3 79 
wm. wal.dO, 
No.8. M.6.2 
Var. spinirostris. gg. i 
Plate I. fig. 5. 
Cambarus immunis, vay. spinirostris, Faxon, Proc. Amer. Acad. Arts and Sci, XX. 146, 1884. 
Known Locality. —Obion Co., Tenn. 
_ C. immiumis is a very common species in Illinois, being especially fre- 
quent in the muddy ponds of the prairies. Mr. H. G. Hubbard has found 
it in muddy pools and ditches connected with the Detroit River, Michigan. 
According to Mr. Hubbard, it does not form burrows, but conceals itself 
among weeds. 
The second form of the male was unknown to Hagen, and was first 
described by Forbes in December, 1876. The first pair of abdominal ap- 
pendages are split for but a very short distance from the tip; the branches 
are thick, and neither of them is dilated, flattened, or channelled at the 
tip, as is the case in the first form. (See Pl. X. figs. 6a, 6a.) The tufts 
of hair-like setze on the inner side of the penultimate and antepenultimate 
segment of the second pair of legs, so characteristic of this species, are 
