CERITHIUM. 155 



a straight longitudinal system, thus producing straight granular costae, the nodes 

 of which are drawn out axially. 



The body-whorl is ventricose and with similar ornamentation ; base full and 

 ornamented with granular spiral lines. Aperture ovate with some traces of an 

 anterior canal. Other indications wanting. 



Relations and Distribution. — The generic position of this curious shell is open 

 to doubt, but it seems to be fulfilling the dictum of Deslongchamps with regard to 

 the " Melanise " of the Inferior Oolite, viz. that they become shorter and stouter in 

 the higher beds. The sudden increase in the body-whorl, however, carries it far 

 beyond even Cerithium subabbreviatum, or the remarkable variety of G. snbscalari- 

 forme from Grove (see fig. 10 a). 



A single specimen from P ]9 Vitney Cross. 



73. Cerithium subglabrum, sp. nov. Plate VIII, fig. 13. 



Description. — Shell elongate, turrited ; spiral angle nearly regular. Whorls 

 about eighteen in number, short, slightly curved to nearly flat ; sutures rather 

 close. But little trace of spiral ornamentation beyond a faint line on each whorl 

 at a short distance from the posterior margin. The longitudinals are well- 

 developed in the apical and subapical regions, but with a tendency to become wide 

 apart. These gradually fail in the last two whorls, though the terminal tubercles 

 are retained. The lines of growth between the costae are visible. 



Body-whorl short, and with but little trace of ornament; base spirally striated. 

 Aperture ovate. Other indications wanting. 



Relations and Distribution. — Evidently related to G. sub scalar if or me ^ but the 

 differences are so marked as to almost exceed the limits of a mere variety. Rare 

 in the Soiverbyi-bed of Bradford Abbas. 



This terminates the list of species referred with more or less certainty to the 

 Vetustum- Subgroup. 



74. Cerithium (species or variety). Plate VIII, fig. 14. 



Description. — Probable length 35 mm., spiral angle about 14°. Shell elongate, 

 subulate, whorls numerous, convex, and well separated by the suture. The 

 spiral lines are fine and numerous, upwards of twelve on the anterior whorls ; one, 

 slightly broader than the others, occupies the shoulder of each whorl, forming 



