152 A REVISION OF THE ASTACIDA. 
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. /eptodactylus, var. Caspia, from the Cas- 
pian Sea near Lenkoran, as smaller than the normal form, the carapace 
smoother, and the margins of the rostrum nearly smooth. It is probably 
an immature stage of A. leptodactylus. 
In Astacus angulosus Rathke, from the Crimea and adjacent region, the fin- 
gers of the male are not elongated, as in Astacus leptoductylus 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. leptodactylus. 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, although it suggested the name to Rathke. The same condi- 
tion is sometimes found in specimens that in all other respects agree with 
the form /epfodactylus, while in some examples of A. angulosus the branchial 
regions are as convex as in A, lepfodactylus. In the shape of the rostrum and 
abdominal pleura A. angulosus approaches A. fliatilis, but it cannot be con- 
fused with that species, on account of the shape of the chela, the double pair 
of post-orbital spines, ete. Forms intermediate between A. angulosus and 
A. leptodactylus, having the rostrum of the latter combined with characters 
belonging to the former, are met with 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. angulosus a variety 
of A, leptodactylus. 
Since this account of the European Astaci was written, Wladimir Schimkewitscht 
has published an insufficient preliminary notice of an Astacus from the neighborhood of 
the town of Turkestan in the valley of the Jaxartes. It is closely related to A. fluviatilis 
and A. leptodactylus, perhaps not specifically distinct from one of these. It seems to be 
subject to considerable variation in the form of the rostrum and telson. According to 
Schimkewitsch it differs from all the allied species in the great development of spiny 
tubercles on the sides of the carapace (there being four on the hind border of the cervical 
* With reference to the presence of 4. leptodactylus in Western Siberia, see Kessler, op. cit., p- 371, 
Middendorff, op. cit., p. 885, and especially Koppen, “ Notiz wtber die Riickwanderung der Dreissena poly- 
morpha Pall. Nebst einem Anhange: Ueber kiinstliche Verpflanzung der Flusskrebse in Russland.” Beitr. 
zur Kenntniss des Russischen Reiches, 2te Folge, Bd. VI., 1883. 
+ Der turkestanische Flusskrebs. (Vorlaufige Mittheilung.) Von Wladimir Schimkewitsch. Zoolo- 
gischer Anzeiger, VII. 339-341, 23 Juni, 1884. 
