468 THE CANADIAN NATURALIST. [Vol. vi. 



converging to tlie apex, where tliey meet at an angle of between 

 seventy and eighty degrees. In one of the two specimens col- 

 lected, there is a flat margin on each side one-sixth the whole 

 width of the shell. Between these two flat margins the remain- 

 der of the shell is gently convex. In the other specimen this 

 central space is slightly convex in the anterior part of the shell, 

 but on approaching the beak it becomes an angular roof-shaped 

 rido-e. The shell is thin, black and shinino- with obscure fluctua- 

 ting, concentric undulations of growth, and with very fine, obs- 

 curely indicated, longitudinal striae. 

 Length nine lines ; width five lines. 



LiNGULELLA ? AFFINIS, Spec. nOV. 

 Fig. 4. 



Ventral valve elongate, conical or acutely triangular. Apical 

 angle about 45*^. ' Front margin gently convex in the middle, 

 rounded at the angles ; sides nearly straight, uniformly converg- 

 ing from the anterior angles to the beak. Surface with very 

 fine longitudinal striae, about ten in the width of one line. 



This species is founded upon the single specimen of a ventral 

 valve above figured. The upper two- thirds is partly worn away 

 in the middle, leaving only the outline in the stone. It appears 

 to have been, when perfect, gently convex, the rostral portion 

 near the beak semi-cylindrical. Length about thirteen lines, 

 wddth nine lines. 



The dorsal valve has not been identified. 



LiNGULELLA? SPISSA, SpCC. noV. 

 Fig. 5, a, b, c. 



Shell sub-pentagonal, or sub-ovate, length and width about 

 equal, sometimes strongly ventricose. Dorsal valve with the 

 front margin straight or very gently convex for about two-thirds 

 the width in the middle ; anterior angles rounded ; sides straight 

 or slightly convex and sub-parallel until within one-third or one- 

 fourth the leno'th from the beak, then converging to the apex, 

 where they form an obtuse angle which varies from 100 to about 

 110 degrees. This valve is generally very convex, sometimes 

 almost hemispherical, the outline on aside view is rather abrupt- 

 ly elevated in the rostral third, depressed convex for a short 

 space in the middle, and then more gently descending to the 

 front margin. Most of the specimens of this valve are eight or 

 nine lines in length, and about the same in width. 



