52 MOLLUSCA FROM THE CRAG. 



shell, figured by Lea (Contributions to Geology, pi. 5, f. 155), but that shell does not 

 appear to be ornamented like our species. The cancellated exterior is scarcely shown 

 enough in the engraving. 



Fusus,* Lam. 1801. 

 Fusus INTORTUS (?). Lam. 



S. Wood. Catalogue 1842. 



A worn and mutilated specimen of a shell which bears a great resemblance to the 

 above Eocene species. It has been for some years in my cabinet, and was found by 

 myself in the Red Crag of Button. It is possible that it may be a London clay specimen 

 washed out of that formation. 



Fusus PORRECTUS (?), Grander. 

 Fusus PORRECTUS. <S. Wood. Catalogue 1842. 

 MUREX PORRECTUS. Grander. Foss. Hant. pi. 2, fig. 36. 



A mutilated specimen also of what appears to be the well-known Barton species. 

 It was found by myself in the Red Crag of Button, but it is not in a condition to be 

 fairly identified. This shell and F. intortus are deeply stained with the ferruginous 

 tinge of the Red Crag, and were probably both introduced into this formation from the 

 London clay. 



PLEUROTOMA,f Lam. 1801. 

 TURRICULA. Schum, 1817. 

 TOMELLA. Sw. 1840. 



Gen. Char. Shell fusiform and turriculate, often thick and strong, generally 

 sulcated or striated transversely ; rarely smooth, sometimes nodose or tuberculated, 

 with an ovate aperture, terminating inferiorly in a canal more or less elongated ; outer 

 lip sharp and thin, furnished with a slit or sinus below the suture ; columella smooth, 

 nearly straight, and in the recent state it has an acuminated operculum, with the 

 nucleus at the sharper and lower extremity. 



This genus comprises a large number of species, the greater part of which are 

 natives of tropical or subtropical regions. None in which the sinus is immediately in 

 the side have hitherto been found in a living state in a latitude so high as that of the 

 British Channel. To this character it is here intended to restrict the genus. In the 

 Eocene formations this genus is exceedingly abundant, both in species and in individuals, 

 as if the climatal conditions of the seas of that period were more immediately favorable 

 to its development. 



* Etym. Fusus, a spindle. 



t Etym. Tl\evpa, the side, and Topfi, an incision. 



