ASTACUS. 129 
Somrre. PoposraNncuin. ARTHROBRANCHLE. PLEUROBLKANCHLE. 
VALS Pee per ate  O) (ep.) of WATS AO) oe wet tO ee ——i()) (ep.) 
VII. 1 1 0 0 =v 
VIII. 1 1 1 0 i 
IX. 1 1 1 0 = 3 
>. 1 1 1 7 =3+r 
XI. 1 l 1 r =3-+r 
NOI eee eee em erst Loe. cote WN, Oo Ao ag =3-+7 
Neate Om erie. OFS. 210) dae oT = il 
6+ ep.+ 6 + 5 + 1+3r=18+3r-+ep. 
The structure of the gills and coxopoditic sete is the same as in the 
Astaci proper. 
2. Astacus (Cambaroides) Dauricus. 
Plate X. figs. 9, 9/ (first abdominal appendages of male). 
Astacus Dauuricus, Patuas, Spicilegia Zoologica, Fase. IX. p. 81, 1772. 
Cancer Dauuricus, PAauuas, |. ¢. 
Dauurische Krebs, Wersst, Versuch Naturgesch. Krabben u. Krebse, IT. 42, 1796. (After Pallas.) 
Astacus leptorrhinus, Fiscunr, Bull. Soc. Impér. Nat. Moscou, IX. 467, Tab. V. fig. 1, 1836. 
Astacus Dauricus, Extcuson, Arch. Naturgesch., XII. Jahrg., I. 94, 1846. 
Astacus Dauuricus, GeRstreLptT, Mém. Acad. Impér. Sci. St. Pétershourg, VIII. 292, 1859. 
Astacus Dauricus, Knsster, Bull. Soc. Impér. Nat. Moscou, XLVIII. 361, 1874. 
Astacus (Cumbaroides) 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). 
8. Astacus (Cambaroides) Schrenckii. 
Plate VI. fig. 3. 
Astacus Schrenckii, Kessuer, Bull. Soc. Impér. Nat. Moscou, XLVIII. 363, 1874. 
Astacus (Cambaroides) Schrenckii, Faxon, Proc. Amer. 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. Schrenchi bears less resemblance to A. Dawricus, from the upper 
part of the same river basin, than A. Japoneus does. On the other hand, 
the chele and abdominal pleura of A. Schrenckii are very much like those 
of A. Dauricus, while in A. Japonicus the chelx are much shorter and broader, 
the abdominal pleura broader and more reunded, than in the Amoorland 
species. 
* The epipodite of the first maxilliped bears no branchial filaments. 
7 
