796 



DIVISIONS OF THE GASTROPODA. 



Fig. 707. - 

 canahculatus, 

 cene. 



the genera Melongena, Fulgur (fig. 707), and Tudida, form portions 

 of the old genus Pyrula, and all possess a pear-shaped ventricose 

 shell, with a short spire and a large body-whorl. Melongena has 

 a short wide canal and nodose or spinose 

 whorls, and is exclusively Tertiary and Recent. 

 Fulgur and Tudida, on the other hand, have a 

 long straight canal ; and both genera have recent 

 representatives, the former commencing in the 

 Miocene, and the latter in the Cretaceous de- 

 posits. 



Family 45. Muricid^e. — In this family the 

 shell has a moderately high spire, and the sur- 

 face is adorned with foliaceous expansions, spines, 

 or well-marked varices. The aperture is round 

 or oval, entire posteriorly, and prolonged an- 

 teriorly into a straight or slightly oblique canal, 

 which is generally partially closed in. The 

 members of this family are all marine, and 

 with the exception of a few Cretaceous forms, 

 they are confined to the Tertiary and Recent periods. 



In the genus Murex (fig. 708) the shell is sometimes elongated, 

 sometimes ventricose, and the surface is adorned with varices in the 



form of longitudinal ridges or 

 rows of spines. The aperture is 

 rounded, and the canal is usually 

 greatly prolonged, and is always 

 partially closed in. Taken in its 

 wide sense, the genus Murex 

 ranges from the Chalk to the pre- 

 sent day, a large number of spe- 

 cies having been obtained from 

 the Tertiary rocks. In the nearly 

 related genus Typhis (fig. 709) 

 there are tubular spines between 

 the varices, and the last of these 

 lodges the posterior siphon, 

 while the canal is completely 

 closed in. The species of Ty- 

 phis range from the Chalk to 

 the present day. Lastly, in the 

 genus Trophon the shell is fusi- 

 form, with numerous narrow varices, the canal being open and 

 slightly bent to one side. The genus is Tertiary and Recent. 



Family 46. Volutid^e. — In this family the shell is turreted or 

 convolute, with a shining, often enamelled, surface, and a large body- 



Fig. 708. — Murex Sedgwickii. 

 (After Zittel.) 



Miocene. 



