GASTROPODA— FUSOIDEA. 777 



more, ribs narrow, twice their width apart, often obsolete on last 

 whorl ; spirals strong ; canal of moderate length, outer lip lirate 

 within. 



Pliocenic of California coast, 



560. H. (Barbarofusus) robusta (Trask). Pliocenic-Recent. 

 Like the preceding but shoulders more flattened and whorls 



more bulging in adult; shell shorter and less slender. 

 Pliocenic-Recent of California coast. 



CLXIV. Exilia Conrad. 



Slender, fusoid shells with sutures not deeply impressed, surface 

 with regular ribs and aperture gradually contracted ^o long canal. 

 Eocenic. 



561. E. pergracilis Conrad. (Fig. 11 33.) Eocenic. 

 About twelve rounded volutions with faintly sigmoidal ribs, 



more than their width apart; straight canal, shorter than spire; 

 spirals fine. 



Midwayan of Alabama and Mississippi. 



CLXV. Lathyrus Montford. 

 Fusiform but thicker and more solid than Fusus; generally 

 with a straight canal shorter than in Fusus; columella with two or 

 three plaits anteriorly; sometimes umbilicated; whorls with ribs 

 and spirals ; outer lip lirate within ; generally angulated. Cretacic- 

 Recent. 



562. L. floridanus Heilprin. (Fig. 11 34.) Eocenic-Miocenic. 

 Whorls round but shoulder flattened; ribs dying away towards 



suture; spirals pronounced with very fine secondary ones; lirae 

 strong ; columella with two obscure plaits ; outer lip with additional 

 lirae in adult specimens. 



Nummulitic (Eocenic) beds of Tampa and Miocenic silex beds 

 of Ballast Point, Florida. 



CLXVI. Streptolathyrus Cossman. 

 Differs from Lathryus in its strongly twisted canal which pro- 

 duces a corresponding change in columella; surface with or with- 

 out ribs. Eocenic. 



