CORALLINE LIMESTONE. 



333 



GASTEROPODA OF THE CORALLINE LIMESTOx\E. 



The most common species in this rock are one of Bellerophon and one of Bucania. These, 

 as well as all the others, are usually distorted by pressure, and otherwise very imperfect. They 

 are nevertheless so peculiar as to be readily recognized, even in that condition, when compared 

 with other species of the same genera from other strata. 



695. 4. PLATYOSTOMA sp. 



PL. LXXVI. Fig. 1. 



The specimen figured is an imperfect cast. It is not unlike P. heviispherica of the Niagara 

 group, but the imperfection of specimen^ renders it impossible to make satisfactory comparisons. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of Johx Gebhahd junior.) 



696. 21. PLEUROTOMARIA SUBDEPRESSA (n. sp.). 



Pl. LXXVI. Fig. 2 o, 6. 



Trochiform ; volutions angular, marked by three carinse on each ; spaces between the carinse 

 marked by oblique strise ; shell rather coarse and strong. 



The specimen figured is imperfect, showing about four volutions : the first one is scarcely 

 distinct in the figure ; one or more of the last volutions are entirely wanting. In its general 

 character this species resembles one in the succeeding rock, but the volutions enlarge much 

 more rapidly from the apex, and the angles are more prominent. 



Fig. 2 a. Profile view of the fragment. 

 Fig. 2 b. View of the apex of the same. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of John Gebhard junior.) 



697. 17. MURCHISONIA^ OBTUSA. 



Pl. LXXVI. Fig. 3. 



Shell elongated ; spire consisting of seven or eight volutions ; volutions rounded, ven- 

 tricose, more prominent on the lower side ; aperture somewhat expanded. 



The specimen is a cast, wanting one volution. The surface is nearly smooth, though there 

 are slight indications on each volution of a carina just below the centre, with bent striffi pro- 

 ceeding from it. The form of the shell is too peculiar to be mistaken. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of ioHTt Gebhard junior) 



