CAMl'.Aia S. 99 



41. Cambarus immunis. 



Plate X. llgs. 6 a, 6 a' (llrsl ubilmniiml ap|>i 'luln^'cs til milk-, form II.). 



^imhn-ux immunis, UAIIKN, 111. Cat. Mus. Com|>. Zofil., No. 111. p. 71, I'l. 1. iigs. 101, 102, PI. III. lig. Kid, 

 I'l. VIII. lig. I),' 1870. (Male, form 1., and female.) 



immunis, SMITH, lie p. U. S. Comui. Fish and Fisheries for 1872 and 1873, p. 039, 1874. (After 

 [iigcn. No description.) 



immunis, Fomu-.s, Bull. 111. Mus. Nat. Hist.., No. I. pp. 4, 19, 1876. (Male, form II., and young.) 

 !i,niiin/ix, liiiXDY, Proc. Acad. Nat. Sci. Pliila., IS77, p. 171. 



,/;///;/, IlKRRR'K, Tent li Ann. Rep. Geol. Nat. Hist. Surv. Minn., for the Year 1SS1, p. 253, 18S2. 

 iiiiiiiHnix, FAXON, Proc. Amer. Acad. Arts and Sci., XX. 140, 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). Illinois : Aux Plains (Coll. U. S. Nat. 

 Mus.) ; Belleville ; Lawn Ridge ; Normal ; Oquawka (Coll. 0. P. Hay). Michi- 

 gan : Detroit River, Detroit. Wisconsin : Milwaukee (Coll. U. S. Nat. Mus.). 

 Minnesota : Richfield, Hcnnepin 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.). 



VAU. spinirostris. 



Plate I. fig. 5. 



I'liiiiliiifiis ii iii H iiis, var. sjii/tifox/i-ix, FAXON, Proc. Amer. Acad. Arts and Sci., XX. 146, 1SS4. 



Known 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 

 t in muddy pools and ditches connected with the Detroit River, Michigan. 

 According to Mr. Hubbard, it does not form burrows, but conceals itself 

 imong weeds. 



The second form of the male was unknown to Hagen, and was first 

 lescribed by Forbes in December, 1876. The first pair of abdominal ap- 

 jenclages are split for but a very short distance from the tip ; the branches 

 ire thick, and neither of them is dilated, flattened, or channelled at the 

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

 )f hair-like setoe on the inner side of the penultimate and antepenultimate 

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



