156 GASTEROPODA OF THE INFERIOR OOLITE. 



a slight belt near the posterior margin. The longitudinal costae are numerous, 

 regular, and slightly arcuate on all the posterior whorls, but become faint and 

 almost effete on the anterior whorls. Other indications wanting. 



Relations and Distribution. — This rare form has a certain resemblance to the 

 finer varieties of C. spinicostatum, and at one time I was disposed to regard it as, 

 possibly, a worn example of that rather abundant species ; but further examination 

 induces me to believe that the differences are not so brought about, since the 

 whorls are more tumid in addition to the great difference in the ornamentation. 

 The anterior portion of the shell is not unlike G. costellatum, Desl. (p. 202, pi. xi, 

 19). As regards the failure of the longitudinal ornaments anteriorly we have 

 similar instances in C. vetustum,, var. seminuda of the Dogger. 



A single specimen in the Sovierbyi-bed of Bradford Abbas. 



75. Cerithium (species or variety). Plate VIII, fig. 15. 



An incomplete specimen. Length of fragment 21 mm., spiral angle about 11°. 

 Shell elongate, subulate. Number of whorls remaining thirteen, short, subconvex, 

 well separated by the suture. The spiral lines on each whorl are about eight in 

 number; longitudinal costae numerous, slightly arcuate, extending from suture to 

 suture, and slightly decussating with the spirals. Upper row of spirals slightly 

 nodular. Other indications wanting. 



This may be an extremely subulate variety of C. spinicostatum, of which the 

 apical portions alone are preserved. A single specimen in Mr. Whidborne's collec- 

 tion, apparently from the Sowerbyi-bed of Bradford Abbas. 



76. Cerithium armatum, Munster, 1844. Plate IX, fig. 1. 



1844. Ceeithium aematum, Miinst. Goldfuss, Petref., t. 173, fig. 7. 



A single specimen from the Sands below the Cephalopoda-bed at North Nibley, 

 though somewhat larger than typical specimens from the Torulosus-schichten 

 of Uhrweiler, answers the description of this species very well. It may be distin- 

 guished from Cryptaulax scobina by having only two extremely spiny spiral belts. 

 The specimen under consideration does not show an aperture, but Mr. Wilson 

 informs me that specimens from the Lias show that this species is a true 

 Cerithium. 



