CAMBAKUS. 99 



41. Cambarus immunis. 



Plate X. ligs, 6 a, 6 a (flrst abdominal appendages of malt-, I'onn II.). 



Cambarus imimmis, Hagen, 111. Cat. Mus. Couip. Zoijl., No. 111. p. 71, PI- I. figs. 101, 102, V\. III. Cg. If.O, 



PI. VIII. flg. 1), 1870. (Male, form I., and lemale.) 

 Cambarus immunis. Smith, Rep. U. S. Coiniii. FisU aud Pishcries for 1872 and 1873, p. 039, 1S74. (After 



Hagcu. No description.) 

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

 Cambarus immunis, Bundy, Proc. Acad. Nat. Sci. Pliila., IS77, p. 171. 



Cambarus signlfer, Hekrick, Tenth Ann. Rep. Geol. Nat. Hist. Surv. Jlinn., for the Year ISSl, p. 253, 18S2. 

 Cambarus immunis, Faxon, Proc. Anier. Acad. Arts aud Sci., XX. 14G, 188-1. 



Kmiva Localities. — New York (Coll. L.A.Lee). Indiana: White Eiver 

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

 Sci.) ; Long Lake, Kendall ville (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. Mu.s.). 

 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: Iluntsville. Mexico: Orizaba (Coll. U. S. Nat. Mus.). 



Ya.ii. spinirostris. 



Plate I. fig. 5. 



Cambarus immunis, var. spinirostris, Faxon, Proc. Amcr. Aead. Arts aud Sci., XX. 146, 1SS4. 



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

 are thick, and neither of them is dilated, flattened, or chiinnelled at the 

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

 of hair-like set03 on the inner side of the penultimate and antepenultimate 

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



