A.STACUS. I-.,, 



SOMITE. PODOBBAHCHM!, ARTIIIiol.KAX, 11, i: PLBUBOBRASCIM. 



AnliTHir. I'nstfrior. 



= (op.) 

 = 2 

 = 3 

 = 3 





= 1 



6-fep. 4- <i 4- _j_ 1 4- 3 > = 18 4-3 /-4-ep. 



The structure of the gills and coxopoditic sette is the same as in tlie 

 Astaci proper. 



2. Astacus (Cambaroides) Dauricus. 



Plate X. figs. 9, 9' (first abdominal appendages of male). 



Astacus Dauiiricus, PALLA.S, Spicilegia Zoologica, Fasc. IX. p. 81, 1772. 



Cancer Dauttricus, PALLAS, 1. c. 



Dauurische Krelis, HERBST, Versucb Naturgesch. Krabben u. Krebse, II. 42, 1796. (After Pallas.) 



Astiiciis leptorrhiims, FISCHER, Bull. Soc. Imper. Nat. Moscou, IX. 467, Tab. V. fig. 1, Ivifi. 



AxliH-iis Dauricus, ERICHSON, Arch. Naturgesch., XII. Jahrg., I. 94, 18411. 



Astacus Da/i/ericiis, GERSTFELDT, Mem. Acad. Imper. Sci. St. Petersbourg, VIII. 292, 1 s.V.i. 



Astacus Dauricus, KESSLEU, Bull. Soc. Imper. Nat. Moscou, XLVIII. 361, 1874. 



A.ititcim (Ci/mbaroidcs) Dauricus, FAXON, Proc. Amer. Acad. Arts and Sci., XX. 151, 1884. 



Habitat. Upper portion of the Amoor River basin as far down as Alba- 

 sin, including the rivers Ingoda, Argoon, Onon, Shilka, and Nercha, It is 

 not found in the Gasimoor, a tributary of the Argoon (Gerstfeldt, Kessler). 



3. Astacus ^Cambaroides) Schrenckii. 



Plate VI. fig. 3. 



Astacus Schrenckii, KESSLER, Bull. Soc. Imper. Nat. Moscou, XLVIII. 363, 1874. 

 Astacus (Cambaroicles) Schrenckii, FAXON, Proc. Amor. Acad. Arts and Sci., XX. 151, 1884. 



Habitat. Lower part of the basin of the Amoor River (Kessler). 



In the form of the rostrum and in the possession of a lateral thoracic 

 spine, A. Sehrcucl;ii bears less resemblance to A. Dauricus, from the upper 

 part of the same river basin, than A. Juponiciis does. On the other hand. 

 the chelte and abdominal pleura of A. ScJircm-Jii! are very much like those 

 of A. Dauricus, while in A. Juponiciis the chelaj are much shorter and broader, 

 the abdominal pleura broader and more rounded, than in the Amoorland 

 species. 



* The epipodite of the first maxilliped bears no branchial filaments. 



