598 NORTH AMERICAN INDEX FOSSILS. 



but narrowing gradually CLXIV Exilia 



%. Aperture abruptly contracted to anterior canal. 



a. 



a. Spire slender, suture deeply impressed. i / . 



i / . Whorls mostly round, ribbed and 



spiralled, an angulation may 



appear in later whorls, canal 



straight a f . 



a'. Protoconch erect, last portion 

 ribbed and ending in a strong 



varix CLX. Fusus. 



a' '. Protoconch mostly covered with 

 fine ribs, not ending in varix, 

 outer lip with slender lirse. 

 CLXIII. Heilprinia. 

 i> '. Whorls round, canal twisted. 



CLXVI. Streptolathyrus. 

 i / . Whorls mostly angular, protoconch 



merging into conch b' '. 



b'. Ribs and spirals characterizing 

 most or all of the whorls, 

 apical portion of protoconch 

 of several whorls, gradually 

 increasing. 



CLXI. Falsifusus. 

 b' . Ribs replaced by spires, apical 

 whorl or protoconch swollen, 

 erect. 



CLXII. Fulgurofusus. 



a. Spire short, thick and few-whorled. 



CLXXVIII. Urosalpinx. 



\\' . Columella with folds or plications i8f. 



1 8f. Shells with ribs and nodes or smooth in adult, 



but not spinose %%. 



%%. Protoconch papillose. 



CLXXIV. Turbinella. 

 %%. Protoconch not papillose b. 



b. Spire slender, fusiform, sutures deep, ribs 



and spirals well developed 2 f . 



2 f . Plications few, strong c> '. 



c' '. Canal shorter than spire.... a' a. 

 a f a. Inner lip strong, often 

 umbilicated, with sev- 

 eral plications ; outer 

 lip lirate. 



CLXV. Latirus. 



a'a. Inner lip with a single 



tooth-like plication. 



CLXXI. Odontofusus. 



c f . Canal as long as spire ; inner lip 



