6o BuivivETiN 5 330 



154 FOSSIL SHELLS. 



jas of Menard, which I^amarck seems inclined to 

 consider as but a variety of the P. glycimeris, 

 Gmel. Our shell is comparatively somewhat short- 

 er than the latter, and its reflected anterior margin 

 distinguishes it from the faujas. 



SERPULA. 



S. granife7'a. PI. viii. fig. 4. Covered with lon- 

 gitudinal, contiguous, slightly elevated, granulated 

 striae. 



Description. Shell subcylindric, contorted, in- 

 ferior side flat ; the whole surface is composed of 

 very numerous, small, contiguous stri^, each con- 

 sisting of a single row of granules ; these series are 

 alternately smaller. 



Diameter of the larger end three-tenths, of the 

 largest specimen two-fifths of an inch. 



The continuity of the tube within, is interrupted 

 by oblique diaphragms. It sometimes approaches 

 the spiral form, and one specimen has three com- 

 plete volutions of much regularity. 



DKNTAEIUM. 



D. atteniiatum. PI. viii. fig. 3. Arcuated ; sur- 

 face marked with from twelve to sixteen rounded 

 ribs, intervening grooves simple ; lines of growth 

 numerous, distinct ; aperture orbicular. 



lycngth nearly one inch and seven-tenths. 



[J. A. N. S., Phila., ist Ser., Vol. IV, 1824.] 



