20 SIXTEENTH REPORT o!t THE CABINET OF NAT. HISTORY. 



♦' LINOULA MANNI ( n. s.)." 



Shell somewhat obovate, the cardinal end being narrower and 

 rounded ; gradually expanding in width for more than two- 

 thirds the length, becoming slightly narrower below, with the 

 baso-lateral angles very abruptly rounded : basal margin nearly 

 straight. Surface marked by fine close concentric striae, which 

 are scarcely elevated above the smooth glossy surface. Shell 

 thin : valves nearly flat. 



One specimen measures three-fourths of an inch in length by half 

 an inch in its greatest width, while the width one-third the 

 length below the posterior end is three-eighths of an inch. 



Two separate valves are all that have been seen of this species, but it 

 differs sufficiently from all the others in these strata to he readily reco- 

 gnized. This and one other are the only species of Lingula, at this time 

 known to me, in the limestones of the Upper Helderherg group. 



The specimens were received from Dr. R. P. Mann, of Milford, Dela- 

 ware county, Ohio. 



Geological formation and locality. In limestone of the age of the Up- 

 per Helderherg limestone, in Delaware county, Ohio. 



" LINGULA LEANA ( n. s.)." 



Shell robust, ovate, subattenuate towards the beak ; margins 

 gradually expanding and curving from the beak for about two- 

 thirds the length, where the shell has its greatest width. Low^er 

 half of the shell very depressed-convex, becoming more convex 

 towards the beak. Shell comparativel}^ thick, lamellose. 



Surface marked by fine concentric striae and faint interrupted 

 radiating strias, which are more conspicuous and continuous in 

 the exfoliated shell. The length of an apparently full-grown 

 individual is eight-tenths of an inch, and the greatest width 

 eleven-twentieths of an inch. 



This species is conspicuously distinct from any others in the Hamilton 

 and Chemung groups, except L. palcBformis^ from which it differs in its 

 greater proportional length and more attenuate form towards the beak. So 

 far as known to me, it is a rare species. 



Geological formation and locality. In some calcareous layers in the 

 Hamilton shales, in Bristol, Ontario county. 



" LINGULA MAIDA (n. s.)." 



Shell linguiform, elliptical, greatest width a little more than 

 half the length, narrowing gently towards either extremity, 



