OF ARTS AND SCIENCES. 151 



shows no trace of tlie deep notch described and figured by De 

 Haan. 



57. AsTACUs (Cambaroides) Dauricus. 



Astacus Dauitricus, Pallas, Spicilegia Zoolog., Fasc. IX. p. 81. 

 1772. 



Dcmurische Krehs, Herbst, Versuch Naturgesch. Krabben u. 

 Krebse, II. 42. 1796. 



Astacus Jeptorrhinus, Fischer, Bull. Soc. Imper. Nat. Moscou, 

 IX. 467, PI. V. fig. 1. 1836. 



Astacus Dauricus, Erichson, op. eft., p. 04. 1846. 



Astacus DavuricHs, Gerstfeldt, Mem. Acad. Imper. Sci. St. 

 Petersbourg, VIII. 292. 1859. 



Astacus Dauricus, Kessler, op. cit., ]>. 361. 1874. 



Ilab. Upper portion of the basin of the Amoor River. 



58. Astacus (Cambaroides) Schrenckii. 



Astacus Schrenchii, Kessler, op. cit., p. 363. 1874. 

 Hab. Lower portion of the basin of the Amoor River. 



59. Astacus Klajiathensis. 



Astacus Klamathensis, Stimpson, Proc Bost. Soc. Nat. Hist., 

 VI. 87. Feb., 1857. — Journ. Bost. Soc. Nat. Hist., VI. 494. 

 April, 1857. 



Astacus Klamathensis, Ilagen, op. cit., p. 93, PI. III. fig. 169. 

 1870. 



Hab. Oregon, Washington Terr., British Columbia (Spence 

 Bate) ; from the higher regions. 



I have examined tiie branchiae, of A. Klamathensis, A. iiigres- 

 cens, and A. Gamhelii, of the American Astaci. In all of them 

 the branchial formula is the same as in A. fiuviatilis, there being 

 three rudimentary branchia? on each side of the thorax. In 

 A. nigresrens the two anterior ones are short, but thick. They 

 are more highly developed in A. Gambclii than in any other spe- 

 cies of Astacus examined, presenting an interesting approach in 

 structure to the perfectly developed branchia. I<:ach of the rudi- 

 mentary branchia; is much larger than in any other species, and is 

 jointed at a short distance from the base. At the joint there are, 

 in the intermediate pair, two short lateral filaments; in the ante- 

 rior and posterior pairs, the main stem bears one filament. 



60. Astacus leniusculus. 



Astacus leniusculus, Dana, Crust. U. S. Explor. Exped., I. 524, 

 PI. XXXIII. fig. 1. 1852. 



Astacus leniusculus, Stimpson, Journ. Bost. Soc. Nat. Hist.. 

 VI. 493. 1857. 



