>o 



172 GASTEROPODA OF THE INFERIOR OOLITE. 



Geol. France, 2 rae ser., vol. 14 (1857), pi. v, fig. 16, &c, p. 547), has a certain 

 resemblance. This species, according to Cossmann, has many synonyms (' L'Etage 

 Bathonien,' p. 94), and is far from being uncommon in the Bathonian of North- 

 East France. C. attritum is tolerably abundant at Weldon, but it is rare to find 

 a specimen of the size figured. 



101. Cerithium abbas, sp. nov. Plate X, figs. 10 a, 10 b, 10 c. 



Description : 



Length of a good-sized specimen . . 60 mm. 



Width of same . . . .14 mm. 



Spiral angle .... 16°— 18 c 



Shell elongate, turrited ; spiral angle regular. Whorls sixteen to twenty, flat, 

 about twice as wide as high, suture close. The posterior whorls are not turrited, 

 and increase as an elongated cone ; lower down a shoulder is developed on the 

 upper part of each whorl, which gives this part of the shell a turrited aspect. 

 The ornaments consist of numerous spiral lines of unequal strength, thick or thin 

 lines frequently alternating ; towards the shoulder one or two lines are stronger 

 than the rest, giving a slight appearance of a zone or girdle. 



The body-whorl is sub-cylindrical, and with ornaments similar to those of the 

 spire, except that in some specimens the rugosities due to increase are very 

 strongly marked. The base is full, rounded, and finely striated spirally. Aper- 

 ture ovate- elongate, with a considerable callus on the columella. Anterior canal 

 well developed, elongate, and slightly reflexed. In section the whorls are ovate- 

 elongate, both outer and inner walls being rather thick. 



Varieties. — In some specimens the whorls, instead of being flat, are subconvex, 

 and almost without any shoulder ; in this variety the body- whorl is not so 

 cylindrical (B). Not figured. 



In another variety, which occurs at Beaminster, the conical outline of the 

 earlier whorls is maintained throughout, so that there is no turriting whatever, 

 the sutures lying in a sulcus or groove ; there is also a slight belt at the anterior 

 margin of each whorl (0). Almost a distinct species. Not figured. 



Relations and Distribution. — Hitherto I have failed to find any species in the 

 Inferior Oolite of Normandy which appears to possess any relationship to the 

 shells above described. Cerithium abbas has been at times taken for a Nerincea, 

 and I believe that it has been so marked in collections. However, the longitu- 

 dinal section shows that the resemblance to Nerincea is external rather than 

 internal. It is placed provisionally under Cerithium until a suitable genus is 

 provided for it and similar shells. Cerithium abbas is tolerably abundant in the 



