OP ARTS AND SCIENCES. 153 



A. Gambelii has the most eastern range of any of the Ameri- 

 can Astaci. It is found in the Great Salt Lake Valley, and in 

 the upper waters of the Snake River, Idaho. From this region 

 it has passed over the divide into the Yellowstone Valley, and 

 invaded the territory of the Cambari as far as the confluence 

 of the Yellowstone and the Missouri. An examination of the 

 physical geography of this region shows that the migration of a 

 Western species into the Mississippi basin at this point is no dif- 

 ficult matter, the divide separating the waters of the Yellowstone 

 from those of the Snake River being very low, hardly above the 

 level of the ancient Yellowstone Lake.* In the U. S. National 

 Museum are two young specimens, labelled, "Willow Creek, 

 Oct. 9, 1872. Dr. Curtis." An added ticket reads, " Wyoming 

 Terr. ? " Willow Creek in Wyoming Territory flows into the 

 South Fork of the Platte, another affluent of the Missouri. Gi- 

 rard's types are said to have come from " California " ; but whether 

 this signifies California as now limited, I cannot say. In the U. S. 

 National Museum are some specimens marked, " Found in bottle 

 containing specimens from Santa Barbara. Dr. Webb." It is 

 doubtful whether these were really collected at Santa Barbara. 

 I have seen no authentic specimens from California. 



64. ASTACUS TORRENTIUM. 



Cancer torrentium (Steinkrebs), Schrank, Fauna Boica, III. 

 247. 1803. 



Astacus torrentium (Steinkrebs), Wolf, Mag. neuesten Zustand 

 Naturkunde (Voigt), XI. 42-45, PI. I. figs. 1, 2. 1806. 



Astacus saxatilis, Koch, Deutschlands Crust. Myriap. u. Arach., 

 Heft 7, No. 1, with fig. (Panzer u. Herrich-Schaffer's Deutsch- 

 lands Insecten, Heft 140, No. 1). 1835. 



Astacus trislis, Koch, op. cit., Heft 7 (140), No. 2, with fig. 

 1835. 



Astacus torrentium, Koch, op. cit., Heft 36 (186), No. 24, 

 with fig. 1841. 



Astacus torrentium, Krichson,f op. cit., p. 92. 1846. 



Astacus saxatilis,^ Erichson, op. cit., p. 92. 



Astacus tristisrf Erichson, op. cit., p. 93. 



* See W. H. Holmes's Report on the Geology of the Yellowstone National 

 Park, in 12th Ann. Eep. U. S. Geolog. Surv. of the Territories, for 1878, Part 

 II. p. 56, 1883. 



t Erichson had an opportunity to examine Koch's types of A. torrentium, 

 A. saxatilis, and A. tristis, and notes their clear specific separation from A.fluvi- 



