CAMBARUS. 99 



41. Cambarus immunis. 



Plat*; X. figs. 6 a, Ga (first abdominal appendages oi male, form II.). 



Cambarus immunis, Hagen, 111. Cat. Mus. Comp. Zpol., No. 111. |> 71, PI. I. 6gs L01, 102, PI. 111. fig. 160, 



PI. \ 111. fig. I), 1870. (.Mali-, form I., anil female.) 

 Cambarus immunis, Smith, Rep, I". S. Comm. Fish and Fisheries fur 1^72 ami 1 s 7 :_; , p. 639, L874. (After 



I [agen. No description.) 

 Cambarus immunis, Fokbks, Bull. Ml. Mus. Nat. Hist., No. 1. pp. 1, L9, 1876. (Male, form II., ami young ) 

 Cambarus immunis, Bi ndy, Proc. Acad. Nat, Sei. Phila., IS77, p. 171. 



Cambarus signifer, IIkkkhk, Tentb Ann. Rep. Geol. Nat. Hist. Surv. Minn., Air the Year 1SS1, p. 253, 18S2. 

 Cambarus immunis, Faxon, Proe. Amur. Acad. Arts and Sei., XX. 146, L88 I. 



Knoivn Localities. — New York (Coll. L. A. Leo). Indiana: White River 

 (Coll. Bost. Soc. Nat. Hist.); Fall Creek, Indianapolis (Coll. Peabody Acad. 

 Sei.) ; Long Lake, Kendallville (Bundy). Illinois : Aux Plains (Coll. U. S. Nat. 

 Mus.) ; Belleville ; Lawn Ridge ; Normal ; Oqnawka (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. Sei. Phila.) ; 

 Ellis (Coll. C. II. Gilbert). Wyoming : near Laramie (Coll. U. S. Nat. Mus.). 

 Alabama : Huntsville. Mexico : Orizaba (Coll. U. S. Nat. Mus. ). 



Yak. spinirostris. 



Plate I. tig. 5. 



arus immunis, var. spinirostris, Faxon, Proc. Amer. Acad. Arts and Sei., XX. 14(5, 1S84. 



Knotvn Locality. — Obion Co., Tenn. 



C. immunis 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 arc split for but a very short distance from the tip; the branches 

 are thick, and neither of them is dilated, flattened, or channelled al the 

 tip. as is the case in the first form. (See PI. X. figs. 6a, (3 a'.) The tufts 

 of hair-like seta? on the inner side of the penultimate and antepenultimate 

 segment of the second pair of legs, so characteristic of this species, are 



