TRENTON LIMESTONE. 95 



131. 5. LINGULA RICINIFORMIS; 



Pi.. XXX. Figa. 2 a, b, e. 



Oval, convex, slightly attenuated towards the beak, which is obtuse ; surface nearly 

 smooth, or with fine nearly obsolete concentric lines. Fine radiating stria; are sometimes 

 visible ; and the surface is sometimes slightly ridged, as if from elevated lines beneath the 

 outer lamina of the shell. 



The general oval form and equal convexity of the shell are almost its only distinguishing 

 characters. It is less attenuated towards the beak than the last, and the surface is not so 

 distinctly striated. 



The length of this species does not exceed -p'y of an inch, with a width of little more than 

 y'y. Compared with figs. 1 a, 6, it is less attenuated towards the beak, and not depressed 

 towards the front, which latter feature appears to be constant in the L. attenuate. That 

 species also becomes more spatulate or expanded towards the base as it increases in size, 

 which is shown in 1 b. 



The figures 2 o, 6, c, are from three specimens, varying in size, but all presenting the 

 same form. 



Position and locality. This species occurs with the last in compact dark limestone near 

 Middleville, Herkimer county. (State Collection.) 



132. 6. hmGUhX MQ}5k\AS {a variety of the last species?). 



Pi.. XXX. Figs. 3 a, b. 



Broadly oval, very obtuse, somewhat attenuated near the beaks, regularly convex, 

 rounded in front ; surface marked by fine radiating striae and less conspicuous concentric 

 lines. 



This shell differs from the last, in its greater proportional width, and almost equally 

 obtuse extremities. Length and breadth about as 5 to 6. 



In. addition to the very fine radiating striae upon the surface of the shell, there are some 

 undulating ridges or wrinkles which are not very distinct. The radiating striae are often 

 obsolete or inconspicuous, and, to the naked eye, the surface appears entirely smooth. The 

 shell is usually less convex than the last species, which it closely resembles. 



Position and locality. In the compact limestone, near the centre of the mass, at Middle- 

 ville, Trenton Falls, &c. 



