ASTACUS. 141 



A. Oue tubercle on each side of the hase of rostrum. 



a. Tip of rostrum uot exceeding tlic distal cud of tlie penultimate segment of antouuulc. 

 Rostrum not cariuate at tlic tip. No spines on the sides of the carapace behind the 

 cervical groove ^i- torrentium. 



h. Tip of rostrum ahnost attaining the distal end of the teniiinal segment of the anleiinule. 

 A keel or median crest near the tip of tlie rostrum. One or more spines on the 

 sides of tlie carapace behind the cervical groove A. palUpes. 



B. Tno tuliercles, oue behind theotlier, on each side of the base of tlie loslriiin. 



a. Margin of rostrum not denticulate. 



a. Margin of rostrum granulated, uot eontiuucd back of the anterior post-orbital 



tuljcrelc. Posterior post-orbital tubercle sliglitly developed A.JIuriutilis. 



0. Margin of rostrum smooth, coutiiuied back on the carapace as a distinct ridge as 

 far as tlie posterior post-orbital tubercle. Posterior post-orbital tubercle well 

 developed, provided with a spine A. Colchicus. 



b. Margin of rostrum deul.ienlatc. 



a. Chela flat, llostrum longer than peduncle of autemiule. liasal angle of external 



border of antcnnal scale spinous A. leplodacti/lus. 



/3. Chela thick. Eostrum equal iu length to peduncle of antc-'iiuule. Basal angle 



of ex.tcrnal border of antennal scale not spinous A. pachypus. 



6. Astacus torrentitun. 



Cancer torrentium (.Steinkrebs), Schrank, Fauna Boica, III. 217. 1S03. 



Astacus torrentium (Steinkrebs), Wolf, Mag. neiiesten Zustand Naturkuude, hcrausgegeb. v. Johann Heiu- 



rioh Voigt, XI. 42-45, Taf. I. figs. 1, 2, 1806. 

 Astacus saxalilis, Kocn, Deutschlands Crustaceen, Myriapoden uiid Araehuiden, Heft 7, No. 1, with fig. 



(Panzer and Ilcrricli-Scliiiircr's Deutschlands lusecten, Heft 140, No. 1), 1835 ? 

 Astacus trislis, Kocir, op. cit., Heft 7 (140), No. 2, with fig., ]8;55 ? 

 Astacus torrentium, Koch, op. cit., Helt 3() (186), No. 24, with tig., 1841. 

 Astacus torrentium, Erichson, Arch. Naturgescli., XII. Jahrg., I. 'J2, 1846. 

 Astacus saxatilis, Erich.sgn, op. cit., p. 92, 1846. 

 Astacus tristis, Erichson, op. cit., p, 93, 1846. 



Steinkrebs, Lereboullet, Comptes Reiidus Acad. Sci. Paris, XXXIII. 379, 1851. 

 Astacus loncjicornis, Lebeboullkt, Mem. Soe. Sci. Nat. Strasbourg, V. 2 (separate pagination), PI. 1. figs. 



2-23 1858. 

 Astacus torrentium (Steinkvehs) (in part), Gerstfeldt, Mem. Acad. Imper. Sci. St. Petersbourg, IX. 574, 



579, 581, 584, 1859. (After Koch, Erichson, and Lereboullet.) 

 Astacus torrentium (Steinkrebs), Klunzinger, Jahresh. Vereins vaterliindl. Naturkuude Wiirttemberg, 



XXXVIII. Jahrg., p. 340, 1882. 

 Astacus torrentium, Faxon, Proe. Amcr. Acad. Arts and Sci., XX. 153, 1884. 



Koch's A. saxaiilk, A. tristis, and A. torrrntlum are without doubt one and 

 the .same species, equivalent to A. torrentium (Schranlt) "Wolf. According to 

 Koch, A. saxatilis is distinguished by a .slightly carinated rostrum, whereas 

 in A. tristis and A. torrentium the rostrum is not carinated ; but Erichson, who 

 examined Koch's types, tells us that there is an indication of a median ros- 

 tral carina in A. tristis and A. torrentium also. The carina is certainly shown 

 in an exasra-erated form in all of Koch's figures. The dark color of ^. tristis 

 came from a coating of mould, according to Erichson, and the broad abdo- 

 men is simply a sexual character. 



