ASTACUS. 143 



Astacus pallipes, Lereboullet, Mem. Soc. Soi. Nat. Strasbourg, V. 7 (separate pagination), PI. II., III. 



figs. 3-3 d 185S. 

 Adacm pallipes, -viw. Jluviis, Leeeboullet, Mem. Soc. Soi. Kat. Strasbourg, V. 0, 1858. 

 Astacus torreiitium (Steiukrcbs) (in jiart), Gerstfeldt, Mem. Acad. Imper. Sci. St. Petersbourg, IX. 577, 



1859. 

 Aftacus saxatllk, Grube, Eiii Aiisflug nacli Triest unci dem Quarncro, p. 73, lS(il. 

 Astacus saxatllls. Heller, Die Crustacceu des siidliclieu Europa, p. '217, Tat'. VII. figs. 3, 5, 1863. 

 Astacus fontiimlls (I'ecrcvisse a. picds blaucs), Carbonniek, L'licrevisse, p. 8, 18G9. 

 Potamoblus astacus, G. B. SowKRBY, Continuation of Leacli's Malacostraca Podophllialma Britauniffi, Nos. 



XVIIL, XIX., Tab. XXXIV. lig. 1, 1875. 

 Astacus fluttiatllis, HuxLEY,* Tlie Crayfisli, passim, and p. 230 in pai-tic'ular, Froutispiece and figs. 1-60, 



"lS80. 

 Astacus torrentlum, Huxley,* cyp. clt., p. 296, fig. 61, a, d, g, fig. 62, a, d, 1880. 

 Astacus pallipes (der Doldeuicrebs), Klunzinger, Jabresh. Vci-eins vateriiiud. Natui-kuude Wurttemberg, 



XXXVIII. Jabrg., p. 311, 1882. 

 Astacus pallipes, Paxon, Proc. Amer. Acad. Arts and Sci., XX. 154, lS8i. 



Under the name " Steinkrebs " the older authors appear to have con- 

 founded A. torrentium and A. paUipcB. They Avere first separated as distinct 

 species in 1858 by LerebouUet wii.h the names A. longicornis and A. pallipes. 

 Gerstfeldt (1859) seems to have had very little material from without the 

 bounds of the Russian Empire. Of the " Steinkrebs " he had seen only five 

 ill-preserved dried examples from the Rhone, which, as appears from his 

 description of them (p. 577), belong to A. pallipes. He considers them to be 

 the same species as that described by Schrank and Koch, i. e. A. torrentium. 

 Compared with A. torreiitium, A. pallipes has a narrower rostrum Avith a 

 longer and narrower acumen ; the median keel is more evident, e.specially 

 near the tip of the rostrum ; the antennse are shorter, and the peduncle of 

 the antenni^ overreaches the tip of the rostrum by only a small fraction 

 of the length of the terminal segment, while in A. torrentium it surpasses the 

 rostrum by the whole length of the terminal segment ; the longitudinal ridge 

 on the lower fiice of the antennal scale is not toothed, as in A. torrentium ; 

 behind the cervical suture are several lateral spines ; the chela? are more 

 coarsely and sparsely tuberculate. For a detailed comparison of these two 

 species, see Klunzinger, op. oil. 



A. pallipes and A. torrentium have a rudimentary pleurobranchia on each 

 side of the penultimate and antepenultimate somites. In all the other 

 species of Astacus which I have examined there is a third pair on the preced- 

 ing somite. The first abdominal appendages of the male A. pallipes are 

 figured by Brocchi, Ann. Sci. Nat., G° Ser., Zool. et Paleontol., Tom. 11., Pi. 

 XIII. figs. 12, 13 {''Astacus fluviatilis" from Vaucluse). They agree in form 



* Huxley leaves tbe question of tlic specific or tlie varietal value of the forms A. iwbllls and A torren- 

 tium (= A.fluviatilis and A. pallipes) uudecided. 



