ii6 BUI.I.ETIN 31 116 



ifera or Lea's of cornuta. Our specimens of this general type 

 are represented by figs. 27-29 (pi. 37). Specimens of the high, 

 alveata Qon. or lunata Lea type (figs. 12-16) are exceedinglj^ 

 abundant in the Claiborne sand at Claiborne. Hence there is no 

 trouble in finding an abundance of ' 'connecting links' ' between 

 this and the average j?!'^;«z7m. 



Types. — The 4 specimens labelled /(3;;///m in the Conradian 

 Collection at the Phila. Academy are doubtless the type speci- 

 mens. The type of alveata is doubtless the rather high and nar- 

 row form labelled alveata, showing 7 primary concentric undula- 

 tions. 



Horizon. — Claiborne Eocene. 



Locality. — Practically all of our identifiable material coming 

 under pomilia and close related forms is from the Claiborne sand 

 at Claiborne. Hence the specimens figured are all from that lo- 

 cality. 



Lucina papyracea Lea, Pi. 38. Figs. 17-21. 



L. papyracea Lea, Cont. to GeoL, 1833, p. 58, pi. i, fig. 31. 



f L. niodesta Con. Amer. Jour. Sci. , vol. i, 1846, p. 403, pi. 4, fig. 13. 



Lea's original description. — Shell orbicular, lenticular, somewhat 

 inflated, concentrically and finely striated, slightly folded behind and sub- 

 emarginate ; substance of the shell thin ; lunula cordate ; beaks rather 

 pointed ; lateral teeth scarcely perceptible ; anterior cicatrix short ; lines 

 of growth indistinctly marked ; cavity of the shell rather shallow ; margin 

 crenulate. 



Diam. 3-2oths, Length 7-2oths, Breadth 7-2oths of an inch. 



Observations. — This species has a general resemblance to the impressa, 

 but differs in being rather less inflated and in being without the deep im- 

 pression before the beaks. The posterior fold of iuipressa is greater, and 

 the lateral teeth are much larger. In the present species the striae de- 

 crease in number on the posterior part and there become squamose. 



Conrad's original description of niodesta runs thus : 



Orbicular, ventricose, thin, with minute, approximate concentric 

 lines ; posterior side with an impressed submarginal fold ; posterior margin 

 truncated, direct ; ligament margin straight and oblique ; beaks promi- 

 nent, medial. 



Dall and Cossmann seem inclined to refer modesta to what we 

 term the /t'wzy/a stock, whereas it seems to us that from Conrad's 



