129 



The structure of the gills and coxopoditic seta} is the same as in the 

 Astaci proper. 



2. Astacus (Cambaroides) Dauricus. 



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



Astacus Dauuricus, Pallas, Spicilcgia Zoologica, Fasc. IX. p. 81, 1772. 



Cancer Dauuricus, Pallas, i. c. 



Dauurische Krebs, Herbst, Versuch Naturgesch. Krabben u. Krebse, II. 42, 1796. (After Pallas.) 



Astacus leptorrhinus, Fisi ber, Bull. Soc. Imper. Nat. Mbsi , IX. 407, Tab. A", fig. 1, L836. 



Astacus Dauricus, Erichson, Arcb. Naturgesch., XII. Jahrg., I. 94, 1846. 



Astacus Dauuricus, Gkustfeldt, Mem. Acad. Imper. Sci. St. Pelersbourg, VIII. 292, 1859. 



Astacus Dauricus, Kkssler, Bull. Soc. Imper. Nat Moscou, \l,\ III. 361, 1874. 



Astacus {Cambaroides) Dauricus, Faxon, Proc. Amrr. Acad. Arts and Sci., XX. 151, 1S84. 



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) Schrenekii. 



Plate VI. fig. 3. 



Astacus Schrenekii, Kessler, Bull. Soc. Imper. Nat. Moscou, XLVIII. 363, 1874. 

 Asian's {Cambaroides) Schrenekii, Faxon, Proc. Amcr. Acad. Arts and Sci., XX. 151, 1 S M. 



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. SehrencM bears less resemblance to A. Dauricus, from the upper 

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

 the chelae and abdominal pleura of A. Schrenekii are very much like those 

 of A. Dauricus, while in A. Japordcus the chelae arc much shorter and broader, 

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

 species. 



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

 17 



