Group of Russian Fusulinse. 419 



sent casts of the chambers of a symmetrical lenticular Fora- 

 minifer. Whj two specific names should have been given to 

 specimens which differ in no material particular it is difficult 

 to say. There can, however, be no question that both pertain 

 to small (probably young) examples of the fossil subsequently 

 described by D'Eichwald as Orobias mqualis ; and it is mani- 

 festly right that the specific name employed by the latter author, 

 associated as it is with the description and figures of the ex- 

 ternal as well as the internal characters of the adult organism, 

 should be employed for this particular form, in preference to 

 any term founded on mere casts of the interior of what are 

 possibly immature specimens. 



My own specimens, from the Miatschkovo limestone (figs. 

 10-13), are of intermediate dimensions, much larger than 

 Prof. Ehrenberg's, but generally smaller than D'Eichwald's. 

 Fragments of larger specimens of similar contour were met 

 with; and it is probable that the species may have considerable 

 range in size. Many of the specimens are split (fig. 12) in 

 Nummuline fashion ; and the fractured surface scarcely differs 

 in any appreciable degree from that of the typical fusiform 

 shell when broken across the centre. The smooth specimens, 

 figs. 17 and 18, represent pretty closely the external features 

 of those figured by D'Eichwald, except that the two faces are 

 not quite equally convex. 



FusuUna antiquior (Rouillier and Vosinsky). 



Nummulina antiquio?; Bouillier and Vosinsky, Bull. Soc. Imp, des Nat. 



de Moscou, he. cit. 

 Orobias mitiquior, D'Eichwald, Lethsea Rossica, loc. cit. 



The salient character of the species described under this 

 name appears to be its bilateral asymmetry ; one surface is 

 greatly more convex than the other ; and the margin of the 

 test is rounded. My material has yielded no specimens pre- 

 cisely corresponding to the original drawings ; but examples 

 unsymmetrically built in various ways are by no means un- 

 common. Perhaps the nearest approach to Rouillier and 

 Vosinsky's figures are numbers 17 and 18 of the Plate; and 

 these specimens are in reality somewhat flatter on the under- 

 side than the drawings make them appear. But those described 

 by the Russian authors were of far finer dimensions, and had 

 the inequality of the two sides much more strongly marked. 

 That they presented no true Nummuline structure was satis- 

 factorily ascertained by D'Eichwald, who founded a new genus, 

 Orobias, for their reception on this account. 



