99 



VOLUTOPSIS, Morch. Shell smooth, ovate, ventricose ; spire short, 

 apex bulbaceous ; last whorl rather large ; aperture very large, the lip 

 considerably expanded ; canal scarcely produced, widely obliquely 

 truncate. Operculum irregularly ovate, with apical nucleus. Dentition, 

 PL 26, figs. 24, 25. 



Subgenus HELIOTROPIS, Dall. Shell thin, sinistral, apex mammillated ; 

 operculum relatively very small. 



SIPHO, Klein. Shell thin, pyriform or fusiform, not tuberculate or spiny, 

 usually smooth and rounded whorls ; spire moderate ; canal produced 

 and recurved. Operculum ovate, nucleus apical. Dentition, PI. 26, 

 figs. 17, 18. 



Subgenus MOHNIA, Friele. Operculum paucispiral. 



SIPHONALIA, A. Adams. Shell ovately-fusiform, sometimes variegated 

 in coloring, rather thin, epidermis very thin, fugaceous ; last whorl 

 ventricose, shouldered, usually nodosely plicate and spirally ribbed ; 

 aperture oval, outer lip thin, columella smooth ; canal rather short, 

 twisted. Operculum ovate, nucleus apical. Dentition unknown. 



Subgenus AUSTROPUSUS, Kobelt. Whorls not shouldered. 



FULGU'R, Moiitf. Pear-shaped, thin ; spire short, the angle of the shoul- 

 der spinous ; body -whorl very large, attenuated below into a rather long 

 twisted canal ; lip and columella smooth, the latter with a single, rather 

 obsolete fold. Operculum ovate, nucleus apical. Dentition of typical 

 form ; rhachidian tooth 5-6 dentate, laterals 5-6 dentate. 



Subgenus TAPHON, H. and A. Adams. Shell dextral, transversely stri- 

 ated, whorls rounded ; aperture ovate, fore-part produced into a long, 

 slightly-recurved canal. 



Subgenus SYCOTYPUS, Browne (Gill). Shell with canaliculate suture, 

 periostraca ciliated, nodulous instead of spinous. Dentition, PI. 26, 

 fig; 20. 



STREPTOSIPHON, Gill. Shell subfusiform ; spire rather short, apex 

 papillary ; whorls angulated at the upper part and tuberculate on the 

 angle ; columella concave, with a double very oblique fold on the lower 

 part ; canal moderately long, twisted ; aperture lirate within. Opercu- 

 culum and animal unknown. Seems to connect Busy con with Tudicla. 



TUDICLA, Bolt. Shell fusiform ; spire short, apex papillary ; aperture> 

 oval ; canal very long, narrow, straight ; columella smooth, flattened, 

 with a single large, or three smaller transverse folds at the fore-part. 

 Operculum fusoid. Dentition unknown. 



