290 



PKOCEEDLTSTGS OF THE GEOLOGICAL SOCIETY. 



[Jan. 4, 



like bivalve, and two or three others, snch as the Monodacna Caspica 

 and Adacna plicata? of Mr. Woodward's list annexed, in the Yalpnk 

 Lake*. 



As I was not provided with my dredges when in the Yalpnk Lake, 

 my living specimens were chiefly obtained by diving for them in 

 different depths beyond 5 and 6 feet. As freshwater shells have a 

 great permanency of character through geologic time, these may 

 in all probability be still found in the upper lakes or basins of the 

 Danube, that must have been in connexion with the Black Sea 

 basin when the latter was a purely freshwater lake, and perhaps 

 when at a higher level, as I believe it to have been. The living 

 Cardium in the Bolgrod Lake could only have been brought there by 

 the Danube; for this has become a freshwater lake by retaining 

 the back-water of that river when flooded at its annual rising ; the 

 Biver Yalpuk being too insignificant to be the real cause of the 

 freshwater condition of the lake. Prior to the formation of the 

 delta, this inlet in the Steppe, as well as those adjacent, must have 

 contained the Euxine shells ; as it was then a mere lagoon open to 

 the Black Sea, just as the Baselm Lagoon now is. Associated with 

 the purely freshwater bivalve found on the shores of the delta, is a 

 very pretty flat bivalve (see specimen sent), which at first I thought 

 must have also been found Irving in the river, or the lakes adjacent, 

 like its then doubtful associate, the Yalpuk Cockle (Cardium). But 

 I at length found it living in the Black Sea, and plentiful also in 

 the equally salt lagoon of Baselm ; so that this is as purely a marine 

 shell as the Yalpuk Cockle is purely freshwater. 



I shall now briefly notice some sections of the formations bordering 

 the southern side of the Danube near Tultcha and Besh Tepeh ; and 

 others on the margin of the Baselm Lagoon, where I obtained some 

 very interesting geological facts and specimens indicating the age of 

 these strata. 



Fig. 4. — Section on the South side of the Danube near Tultcha. 



Fig. 4. Kishla. Danube. 



Trap' 



b. Highly inclined siliceous rocks. 



* Mr. Woodward's list of the recent shells obtained by Capt. Spratt on the 

 freshwater lake of the Steppe adjacent to the Danube : — 



Paludina vivipara. 



Melanopsis acicularis. 



Lithoglyphus naticoides. 



Bissoa (Hydrobia), sp. 



Neritina nuviatilis, var. Danubialis. 



Planorbis corneus. 



LinmaBa, sp. (aff. pahistris). 



Cardium, sp. 



, sp. 



Monodacna Caspica ? 

 Adacna plicata. 



, sp. 



Dreissena polymorpha, adhering 

 to Cardium. 



