152 A KEVISION OF THE ASTACID.55:. 



sources of the Ural River are not remote from those of the Ui, it is possible 

 that a spontaneous migration from the former into the latter has taken place.* 



Eichwald describes and figures A. leptodadi/hs, var. Caspin, from the Cas- 

 pian Sea near Lenkoran, as smaller than the normal form, the cai-apace 

 smoother, and the margins of the rostrum nearly smooth. It is probably 

 an immature stage o( A. Icptodacti/hts. 



In Astacus awjuloms Rathke, from the Crimea and adjacent region, tlie fin- 

 gers of the male are not elongated, as in Adacus leptodadylm Eschscholtz, so 

 that the hand has much the same form as in the female of the latter species. 

 The rostrum, moreover, is broader, with its margins more nearly parallel 

 from the base to the lateral spines, and with its median carina prominent 

 and toothed toward the apex ; the abdominal pleura are shorter and broader 

 than in A. leptodadylus. The flattening of the sides of the carapace, by 

 which an angle is formed by the dorsal and lateral faces, is not characteristic 

 of this form, althoiia-h it sua-a-ested the name to Rathke. The same condi- 

 tion is sometimes found in specimens that in all other respects agree with 

 the form kjdoduciylus, while in some examples of A. angulosus the branchial 

 regions are as convex as in A. lepiodadijlm. In the shape of the rostrum and 

 abdominal pleura ^^1. anrpdosus approaches ^.^/(m/iV/s, but it cannot be con- 

 fused with that species, on account of the shape of the chela, the double pair 

 of post-orbital spines, etc. Forms intermediate between A. augnlosiis and 

 A. Icptodadi/hs, having the rostrum of the latter combined with characters 

 belonging to the former, are met Avith in the Sulak River, which flows into 

 the Caspian south of the Terek on the northern side of Mount Caucasus 

 (Gerstfeldt). It seems natural, therefore, to consider A. aiif/ulosus a variety 

 of A. Icpiodadylm. 



Since this account of the European Astaci was written, Wladiniir Schimkewitsclit 

 has published an insufficient preliminary notice of an Astacus from the neighborhood of 

 the town of Turkestan in tlie valley of the Jaxartes. It is closely related to A. Jiuviatilis 

 and A. leptodadylus, perhaps not specifically distinct from one of these. It seems to be 

 subject to consideral)le variation in the form of the rostrum and telson. According to 

 Schimkevvitsch it differs from all the allied species in the groat development of spiny 

 tubercles on the sides of the carapace (there being four on the hind border of the cervical 



* With reference to tlie presence of A. lep/odacfylits in Westeru Siberia, see Kcssler, op. cit., p. 371, 

 MiddcndorIT, op. cit., p. SS5, and especially Koppen, " Notiz iiber die Kuclcwanderung der Vreissena poly- 

 morpha Pall. Nebst eincra Anhange : Ueber kunstliche Verpflanzung der Flusskrebse in Russland." Beitr. 

 zur Kenutniss des Riissisclien Reiclies, 2te Polge, Bd. VI., 1S83. 



f Der turkestauisclie Flusskrebs. (Vorliiufige Mittlieiluug.) Von Wladimir Scliimkewitscli. Zoolo- 

 gischer Anzeiger, VII. 339-341, 23 Juni, 18Si. 



