ASTACUS. 141 



A. One tubercle on each side of the base of rostrum. 



a. Tip of rostrum not exceeding the distal cud of the penultimate segment of antenuule. 



Rostrum not carinate at the tip. No spines on tlie sides of the carapace behind the 



cervical groove A. torrentium. 



b. Tip of rostrum almost attaining the distal end of the terminal segment of the anteuuule. 



A keel or median cresl near the tip of the rostrum, due or more spines ou the 



sides of the carapace behiud the cervical groove l.pallipes. 



B. Two tubercles, one behind the other, ou each side of the base of the roslruin. 



</. Margin of rostrum not denticulate. 



ii. Margin of rostrum granulated, not continued hack of the anterior post-orbital 



tubercle. Posterior post-orbital tubercle slightly developed I. fiumatilis. 



/3. Margin of rostrum smooth, continued back on the carapace as a distinct ridge as 

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



developed, provided with a spine . A. Golchkus. 



b. Margin of rostrum denticulate. 



a. Chela Hat . Rostrum longer than peduncle of antenuule. Basal angle of external 



border of autennal scale spinous I. leptodactylus. 



fi. Chela thick. Rostrum equal in length to peduncle of antenuule. Basal angle 



of external border of autennal --rale nut spinous /. pachgpus. 



6. Astacus torrentium. 



Cancer torrentium (Steinkrebs), Schrank, Fauna Boica, III. 247, 1803. 



Astacus torrentium (Steinkrebs), Wolf, Mag. neuesten Zustand Naturkunde, bcrausgegeb. v. Jbhann Hein- 



ricb Voigt, XL 42-45, Taf. I. tigs. 1. 2, L806. 

 Astacus saxatilis, Koch, Deutschlands Crustaceen, Myriapoden und Arachniden, Heft 7, No. 1, with fig. 



(Panzer and I lerrieh -SehaH'cr's Deutschlands Inscetcn, Heft 110, No. 1), 1S35 ? 

 • trislis, Koch, op. <■;/., Heft 7 (140), No. 2, with fig., L835 ? 

 Astacus torrentium, Koch, op. cit., Hefl 36 (186), No. 24, with fig., 1841. 

 Astacus torrentium, Erichson, Arch. Naturgesch., XII. Jahrg., I. 92, 1846. 

 Astacus saxatilis, Erichson, op. cit., p. 92, 1846. 

 Astacus tristis, Erichson, op. cit., p. 93, IS Hi. 



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

 Astacus longicornis, LerebouILET, Mem. Soc. Sci. Nat. Strasbourg, V. 2 (separate pagination), PI. I. tigs. 



2-2-J, 1858. 

 Astacus torrentium (Steinkrebs) (in part), Gerstfeldt, Mem. Acad. [mper. Sci. St. P6tersbourg, IX. 57 t, 



579, 581, 584, L859. (After Koch, Erichson, and Lerel [let.) 



i (Steinkrebs), Ki.i \/,im;eu, Jahresh. Vereius vaterlandl. Naturkunde Wurttemberg, 



XXXVIII. Jahrg., p. 340, 1882. 

 Astacus torrentium, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 153, 1884. 



Koch's A. saxatilis, .1. tristis, and A. torrentium are without doubt one and 

 the same species, equivalent to A. torrentium (Schrank) 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, teik us that there is an indication of a median ros- 

 tral carina in .1. tristis and A. torrentium also. The carina is certainly shown 

 in an exaggerated Eorm in all of Koch's figures. The dark color of .1. tristis 

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

 men is simply a sexual character. 





