1862.] AUSTIN SIBERIA. 73 



ridges, which together compose a branch or spur, or what may be 

 termed a parallel wave, of the great Daourian chain. 



With regard to the age of the fossiliferous strata, some Ammo- 

 nites and Ceratites were given to me in Siberia, which were said 

 to have come from the neighbourhood of Yakootsk and the banks of 

 the Lena. Mr. Etheridge has had the kindness to examine them, and 

 he assigns the Ammonites to the " middle division of the Oolites "*, 

 and the Ceratites to the Trias. Another Ammonite appears to be the 

 A. virgatus of von Buch, and is therefore undoubtedly from the Lower 

 Oolite. The cliffs forming the right bank of the Angara, about 30 

 versts below Yakootsk, are formed of sandstone containing beds of 

 coal several inches in thickness. A specimen of Fern taken from 

 these beds renders it probable that they are of Oolitic age. 



Several specimens of Rhynehonella cynocephala, found in what 

 appeared to be a bed of alluvium near Yerchne-oudinsk, and which 

 are nearly perfect, having still a soft coat of shelly matter, appear to 

 show the occurrence of the Inferior Oolite there. 



The connexion, however, between the shale containing the Fish 

 and Estherice and the other fossiliferous deposits is not apparent. 

 Dr. von Middendorf must therefore have pronounced the former to be 

 Lias through the evidence which he derived from these fossils. It is 

 possible that the striped schist found in the neighbourhood of Nert- 

 chinsk may be a continuation of the same strata in an altered form, 

 as it very much resembles them in many respects. 



It may be presumed, from the presence of the fossil fish associated 

 with Estherice, and two shells which appear to be a species of Lim- 

 nceus, or possibly Paludina, as well as from the relation of the fish 

 (as determined by Sir Philip Egerton) to Aspius, that the shale is of 

 lacustrine origin. 



Note on Estheria Middendorfii. 

 By Professor T. Rupert Jones, F.G.S. 



This is a well-marked species of that interesting genus of Phyllo- 

 podous Crustaceans which appears to have its representatives in the 

 freshwater or brackish deposits of nearly all the great geological 

 groups of strata, from the Devonian to the existing period. 



Estheria Middendorjii-f occurs in great numbers in grey shale 

 found on the River Toorga in Siberia, and was first regarded by Mid- 

 dendorf as a shell, and then noticed and figured by J. Miiller as a Lim- 

 nadia (see references in Mr. C. Austin's paper, above). The carapace 

 agrees well in its characters with that of Estheria, both in contour, 

 concentric ridges, and sculptured interspaces. It is relatively large 

 among its congeners, recent and fossil, being |-ths of an inch long ; 

 few of the known forms attaining the length of half an inch (ex- 

 cepting the somewhat Limnadioid Estheria Birchii of Australia, which 



* The species appear to be Ammonites cordatus and A. plamda ? ; but the 

 former resembles in some respects A. Chamusetti. 



t Described and figured in my " Monograph of Fossil Esfherm," PalaBonto- 

 graphical Society. 



