GASTROPODA— PLEUROTOMIDM. 



801 



concave shoulders and short, sharp riblets on the shoulder angle 

 and just below it. 



Midwayan of Alabama and Texas. 



622. P. (Hemipleurotoma) childrani Lea. (Fig. 1 176.) Eocenic. 

 Aperture one third of the length of the shell ; shoulder concave 



with moderate sinus in lip; angle pronounced, strongly tubercled; 



suture channeled; surface with strong spirals, generally granulated. 



Aquia formation of Atlantic coast; Chickasawan of Gulf coast. 



623. P. moorii Gabb. (Fig. 1 177.) Eocenic. 

 Slender, with long, contracted canal, shoulders moderately con- 

 cave, with notch; shoulder angle carinate, a second weaker carina 



FlG. 1 176. Pleurotoma {Hemipleu- FlG. 1177. Pleu- FlG. II 78. Pleuro- 



rotoma) childrani, much enlarged, rotoma moorii. (Aft- toma terebralis. (After 

 (Md. Survey.) er Harris.) Harris.) 



cn body of whorl, just above the suture, the space between the 

 two being concave ; surface with spirals and lines of growth only. 

 Chickasawan (Lignitic) of Alabama and Texas. 



624. P. terebralis Lamarck. (Fig. 1 178.) Eocenic. 

 Like the preceding but broader, the upper angle more strongly 



carinate and faintly tubercled; the lower carina and the stronger 

 spirals also granulate. 



Midwayan of Gulf States, also European. 



625. P. (Hemipleurotoma) albida Perry. (Fig. 1179, a.) 



Oligocenic-Miocenic. 



Canal less than half the length of the shell; shoulder with a 



marked median angulation ; body with a strong carina at the suture 



and a fainter one between this and the main angulation which bears 



the notch; additional spirals on body whorl. 



