CLINTON GROUP. 



85 



Position and locality. In the upper green shale of the group at Rochester, and in the same 

 poshion at Sodas ; also in the shale beneath the ore bed in Wolcott. {.suite Co/UctUm.) 



475. 6. TELLINOMYA LATA. 



PL. XXVII. Fig. 7. 



Ovate ; anterior extremity broadest, short and rounded, narrowing somewhat abruptly from 

 the beak to the posterior extremity, which is acutely roundeil ; beak scarcely elevated above 

 the cardinal line ; surface marked with fine, scarcely elevated concentric strias. 



This shell has the general appearance of the succeeding species, but it is proportionally much 

 broader, and more abruptly narrowed towards the posterior extremity. 



Podtion and locidity. This species has been found only in the shale beneath the ore bed 

 in Wolcott, Wayne county. 



476. 7. TELLINOAIYA MACH.^RIFORMIS. 



Pl. XXVII. Fig. 8 a, b, c, d, and 9. 

 Nucula machcBriformis. Hall, Geol. Rep. 4lh Dist. N. York, 1843, pag. 7(5, fijj. 2. 

 Shell oval-ovate, much elongated ; anterior side short, rounded ; posterior side very much 

 extended, and gradually narrowed towards the extremity ; beak scarcely prominent ; cardinal 

 line extending about two-thirds the length of the shell ; length nearly twice and a half the 

 height ; surface marked by fine equal concentric strife, which are scarcely visible to the naked 

 eye. 



Fig. 8 a. The left valve of an individual of ordinary size. 



Fig. 8 b. The right valve of a large individual. 



Fig. 8 c. The right valve of a smaller individual. 



Fig. 8 d. A small portion of the surface much enlarged, showing the concentric strice. 



These specimens are all of entire individuals, having the valves closely compressed. 



Fig. 9 {Cypricardia angusta, Geol. Rep. 4th District, pag. 76, fig. 6). This fossil appears to be 

 identical in its surface markings and general character with the preceding. The ex- 

 treme narrowness of the valves appears to have been produced by pressure, which 

 has otherwise left the shell uninjured. 



This is the most abundant species of bivalve shell in the group ; and it will be readily re- 

 cognized by its elongated form, and proportionally short anterior extremity. It is extremely 

 thin and delicate, having suffered more from pressure than any other species. The shell is 

 rarely preserved in a perfect condition ; and the specimens figured, though having both valves 

 united, scarcely retain any marks of the stria?, though the substance of the shell still remains. 



