REPORT OF THE DIRECTOR I9IO 



177 



Lingula eboria nov. 



Shell small, extremely thin, elongate elliptical, twice as long as 

 broad, moderately convex for these shells, especially in umbonal 

 region, posterior end somewhat more narrowly 

 rounded than the anterior but not angulated. 

 Larger growth lines apparently with thicker shell 

 than the intermediate spaces which show very 

 faint concentric marks. 



Dimensions. Length, 3.5 mm; width, 1.8 mm. 

 Greatest diameter near the middle of the shell. 



Remarks. This shell is very similar to L. 

 1 i g e a Hall, from the upper Hamilton, but is ■^^^on.''^"'®' '" °pp°^'" 

 less pointed at the beak and more tapering Oyster basin. Coffin i. 

 anteriorly and does not appear to be thicker at the margin. This 

 might be governed, however, by the occurrence of the thickening 

 of the shell at the growth stages. 



It is less acute posteriorly than the figure of a shell identified as 

 L. m e m b r a n a c e a by Herrick, but it is very closely related 

 to it, if not identical with it. It is closely related to L. a 1 b i- 

 p i n e n s i s , as figured and defined by Girty from the Moorefield 

 shales. It is also a close relative of L. p a r a 1 1 e 1 a Phillips. 



Lingula eborianov. 



Orbiculoidea limata nov. 

 Shell small, extremely thin ; pedicle valve nearly flat and almost 

 circular, sometimes slightly elongate longitudinally ; aperture reach- 

 ing about half way to the periphery, narrow. 

 Brachial valve with beak moderately elevated 

 and located well toward posterior margin. 

 Surface marked with strong, thick circles of 

 shell between which are small, faint concen- 



Orbiculoidea limata tric marks 



B?Sar1rdVedicie valves DimenswHs. Length, 5.75 mm; beak, 4 



Oyst'er basin. Coffin I. ^^^^^ ^^^"^ pOStcrior margin. 



Strophalosia nebraskensiformis nov. 

 Shell of medium size, subquadrate. Immediately beneath the 

 beak of the brachial valve, viewed externally, is a minute convexity 

 back of the umbonal concavity of the valve. Valve convex in central 

 portion, and between the ears and the central part two slight con- 

 cavities lie either side of the anterior median convexity. Interior of 

 valve with a long median septum reaching nearly to the front of the 



