PTEROPODS. 217 



PTEROPODS. 



Tentaculites incurvus SHUMARD. 



Plate xxxv, fig. 3. 



Tentaculites incurvus Shumard, 1855 : Geol. Sur. Missouri, Ann. Rep., p. 195, 

 pi. B, figs. 6a-b. 



Shell very small, attenuated, carved, with prominent, sharp 

 annulations extending to the tip ; at the large extremity there 

 are four, five to six rings in the space of an eighth of an inch, 

 and the intervening spaces are about double the width ; but 

 near the tip the rings are much closer together, and there are 

 from eigh een to twenty in the eighth of an inch; the whole 

 number of rings amounts to thirty-five. The surface is covered 

 with fine longitudinal striae, which cross the rings, as well as 

 the spaces. In well-preserved specimens very fine transverse 

 striae can be perceived. ( Shumard.) 



Horizon and localities. Lower Silurian, Girardeau lime- 

 stone: Cape Girardeau. 



Conularia marionensis SWALLOW. 

 Conularia marionensis Swallow, 1860: Trans. St. Louis Acad. Sci., p. 656. 



Like C. missouriensis, but with a greater number of trans- 

 verse costae, which are also granulated. 



Horizon and localities. Lower Carboniferous, Hannibal 

 { Vermicular) shales ( Kinderhook ) : Hannibal. 



Conularia triplicata SWALLOW. 

 Conularia triplicata Swallow, 1860 : Trans. St. Louis Acad. Sci. , p. 657. 



Small, with the costae triple ; one large median rib with a 

 smaller one on each side. 



Horizon and localities. Lower Carboniferous, Hannibal 

 shales (Kinderhook): Marion county. 



