GASTROPODA— TURRITELLIDJE. 



731 



■^1 



convex with 5 or 6 strong primary spirals, with weaker second- 

 aries, and still fainter tertiaries. Suture depressed. 

 Ripleyan (Monmouth) of New Jersey and Alabama. 



423. T. encrinoides Morton. (Fig. 1062.) Cretacic. 

 Center of whorl flattened, basal angle pronounced, whorls em- 

 bracing to within a short distance of the angle. 

 About 3 or 4 strong primary spirals, with 

 strong secondary ones between. Internal 

 mold more compact than in T. vertebroides. 



Ripleyan (Navesink) of New Jersey and 

 Alabama. 



424. T. trilira Conrad. (T. trilineata H. and 

 V.) (Fig. 1063.) Cretacic. 

 Whorls slightly convex, sutures depressed, 



three strong spirals, a fourth generally covered 

 at the suture. 



Ripleyan of New Jersey, Alabama, Missis- 

 sippi, Navarro of Texas, Arkansas, etc. 



425. T. tippana Conrad. Cretacic. 

 Differs from the preceding in the scarcely 



depressed suture and in having four spirals, 

 the lower three equidistant, the upper more 

 distant and stronger, and in the presence of a 

 few intercalated spirals. 



Ripleyan of New Jersey and Mississippi. 



426. T. mortoni Conrad. (Fig. 1064.) 

 Volutions angulated, shoulder slightly concave, with two or 



three primary and several secondary spirals. Keel very angulate 

 in specialized varieties (T. postmortem, Fig. 1064, d). Body whorl, 

 below angulation, mostly covered by succeeding whorl. Aperture 

 subquadrangular. 



In the lower Pamunkey (Aquia formation) of Maryland and 

 Virginia — especially abundant on Aquia Creek. Midwayan of 

 Alabama, Texas, Arkansas, Mississippi, Tennessee. Occurs often 

 as internal mold (Fig. 1064, b). 



427. T, (Mesalia) vetusta Conrad. Eocenic. 

 Sutures sharply impressed, but shallow, spirals fine, alternating 



in size ; ribs arcuate, indistinct, generally obsolete ; whorls slightly 



Fig. 1063. Turri- 

 tella trilira. (After 

 Hill.) 



Eocenic. 



