No. 109. 



183 



posterior, one large and strongly impressed, the other smaller, 

 lying above and between the larger one and the hinge-line ; 

 pallial impression simple. 



1, 2, 3 : Tellinomya nasuta. 



4, 5 : T, dubia. 



G, 7 : T. cuneata^ 



In the larger species known, the hinge-line is only slightly arcuate ; 

 while among the other species we find many variations in the curvatuic, 

 and it sometimes becomes distinctly angular, as in T. cuneata. In some 

 species the teeth on either side of the beak curve outwards from it, and in 

 others inwards towards the beak on both sides. The teeth are often very 

 minute immediately beneath the beaks. 



The shells of this genus vary from elliptical to ovate and subtriangular 

 forms, many of them being contracted on the posterior side ; they are 

 usually of moderate thickness, though one species is very thick and stroll^^ 

 Some of the species have a distinctly impressed lunule. The lesser mut^t.■M- 

 lar impression is often a small pit placed directly beneath the hinge-1 ip . 

 and between it and the large muscular impression. The beaks are usuai'v 

 of medium size, pointed, rarely ventricose, approximate or in cont-M L 

 never subspiral. 



* The specimens above figured ^Yere collected at Pauquette's Rapids on the Ot1:- .■ ; 

 River, in beds Ij'ing at the junction of the Trenton and Black-river limestones. 1 .l.>. 



