GENUS VITULINA. 411 



Surface covered by minute papillae. Substance finely punctate. 



In the interior of the ventral valve, the margins of the foramen are 

 extended in two strong teeth, which are supported on the lower and 

 lateral margins by a callosity of the shell. Beneath the apex, a strong 

 callosity or false area extends across the valve and reaches to the base 

 of the teeth. This callosity is visible in the foramen, and from its lower 

 margin proceeds a «lender median septum (fig. 1 h). On each side of this 

 septum, at its junction with the transverse callosity, there is a small 

 pit for the occlusor muscle ; and beyond this a broad flabelliform area 

 for the divaricator muscular attachments. These features are shown in 

 the cast, fig. 1 i. ^ 



In the dorsal valve, there is a strong median ridge or septum which 

 terminates in a slightly lobed cardinal process ; on each side of this are 

 the crural processes, and between these and the margin are the teeth 

 sockets. 



Figures 1 a, b, are of the largest specimens observed. Figures 1 c and 1 d are enlarged, 

 showing the character of the plications and the pustulose surface. Figures 1 e, f, are 

 enlargements from an entire specimen : the profile, us given, represents the dorsal area as 

 proportionally too wide. The interiors of the valves and the cast of the ventral valve are 

 enlarged two diameters. 



Geological formation and localities. This species was first observed in a single 

 individual among specimens collected at Canandaigua lake, and was afterwards 

 found at York in Livingston county. More recently, and since the engravings 

 were completed, Mr. "WinxFiELD has found the fossil in considerable numbers 

 near Tully and at Tinker's falls in Onondaga county. 



