356 CRAYFISHES. 
the distal end of the median rib. Length, 90 mm., length of carapace, 41 mm., 
width of carapace, 20 mm., width of base of rostrum, 6.5 mm., length of rostrum, 
9 mm., length of areola, 11.5 mm., breadth of areola, 7 mm., length of antennal 
scale, 7 mm., greatest breadth of do., 4 mm., length of larger claw, 31 mm., 
breadth of do., 17.5 mm., length of superior margin of hand, 10 mm., length of 
dactylus, 19 mm., length of smaller chela, 23 mm., breadth of do., 9 mm., length 
of dactylus, 16 mm. 
There are four specimens of this species in the U. S$. National Museum from 
the rivulets of MM. Bock and Jones, Lake Nahuel Huapi, on the eastern slope 
of the Cordilleras in Argentina. The chelipeds are preserved in three of these 
specimens; in two the larger claw is on the left side, in one it is the right, as in 
the Paris specimen. 
The tip of the rostrum is setose in this species, and in most cases there are 
a pair of minute, horny, bead-like lateral teeth just back of the point of the ros- 
trum. The rostrum is therefore essentially like that of P. bimaculatus. From 
the latter the present species differs in having much stouter, shorter-fingered, 
more heavily tuberculated claws, and a somewhat longer metathorax and nar- 
rower areola. 
Parastacus agassizii (= bimaculatus) has been recorded from Lake Nahuel 
Huapi by Ortmann (Proce. Amer. Philos. Soc., 41, p. 293). The specimens 
should be examined anew with reference to the possibility of their belonging to 
the present species, P. spinifrons ? 
Specimens from Puerto Montt, Lake Llanquihué, on the opposite slope: of 
the Cordilleras, in Chile, are said by Doflein (Sitzungsber. Akad. Wissensch. 
Miinchen, 1900, 30, p. 133) to agree wholly with my description of P. agassizii! 
(= bimaculatus). 
PARASTACUS BIMACULATUS (Philippi). 
Astacus bimaculatus R. A. Pururprr, Anales Universidad Chile, 1894, 87, p. 378 (Chile). 
Parastacus agassizit Faxon, Proc. U.S. Nat. Mus., Feb. 17, 1898, 20, p. 690, pl. 70, figs. 4,5 (Taleahuano, 
Chile). Dorxery, Sitzungsber. Akad. Wissensch. Miinchen, 1900, 30, p. 132 (Puerto Montt, Lago 
Llanquihué, Chile). Lenz, Zool. Jahrb., Supp., May 2, 1902, 5, p. 736 (Tumbes, Chile). Porter, 
Revista Chilena de Hist. Nat., Dec. 31, 1904, 8, p. 258, Pl. 9 (Contulmo and Chillin, Chile). 
! The error in the branchial formula of P. agassizii as it appears in my paper in the Proc. U.S. Nat- 
Mus., 1898, 20, p. 692, has been pointed out by Doflein. This error was due to an unfortunate disloca- 
tion of the table in printing, as is evident on comparing the table of the branchial arrangement in the 
genus Parastacus on p. 683. 
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