GASTEROPODA. 09 



Sect. a. DEXTRAL. 



1. Cerithium tricinotum (?) Broc. Tab. VIII, fig. 1 a — b, and 2. 



Murex tricinctus. Broc. Conch, foss. Subap. pi. 9, fig. 23, 1816. 

 Cekithium tricinctum. Nyst. Coq. foss. de Belg. p. 539, pi. 42, fig. 7, 1844. 



Dujardin. Mem. Soc. Geol. de France, torn, xi, p. 288, 1837. 

 Cerithium punctatum. Woodward. Geol. of Norf. t. 3, fig. 29, 1833. 

 — S. Wood. Catalogue 1842. 



C. Tesld elonyato-turrita, aqualiter granulata ; anfractibus numerosis, planulatis, 

 triplici serie yranulorum cinctis, columella sine plicatd. 



Shell elongato-turreted ; spire subulate and elevated ; volutions flat, ornamented 

 with three equally granulated bands ; aperture subquadrate, outer lip curved ; colu- 

 mella without a fold. 



Axis, 2 inches. 



Locality. Red Crag, passim. 



Mam. Crag, Thorpe and Bramerton. 



Although this species is common enough in the Red Crag, all the specimens I have 

 seen are in bad condition. In the Subapennine shells, and generally in those from 

 Touraine, there is a distinct fold upon the columella above, and independent of that 

 projection which forms one side of the basal canal. It is possible it may be worn 

 away in the Crag shells, as, in some specimens from the Touraine beds, which were 

 given me by Mr. Lyell, this character has quite disappeared, and it was by that alone 

 it could be distinguished. In more perfect specimens, strias or ridges on the base 

 of the volutions may be observed, which become larger toward the outer edge, like 

 those upon the Touraine shells. Specimens are sometimes found with four bands, 

 while others have only two. Some are so much eroded and altered as to have the 

 volutions distinctly convex. 



Fig. 1 (a) is from the Mam. Crag, Thorpe. 



1 (6) from the Red Crag, Sutton. 



2 is an eroded specimen, with very convex volutions, and is probably only 

 an altered form of this species. 



2. Cerithium variculosuh. Nyst. Tab. VIII, fig. 3, 3 a. 



Cerithium variculosum. Nyst. Coq. foss. de Belg. p. 540, pi. 42, fig. 9, 1844. 

 Cerithium punctulum. S. Wood. Catalogue 1842. 



C. Testa elonyatd, turritd, subulatd ; apice acuminata; anfractibus 9 — 10, convexius- 

 culis ; lonyitudinaliter plicatis ; transversim quadristriatis ; striis elevatis, tuberculato- 

 nodosis, labro acuto. 



Shell elongate, turreted, and regularly tapering, with an acuminated apex ; 

 whorls 9 — 10, slightly convex, covered with four granulated bands ; outer lip sharp ; 

 base emarginate, without a canal. 



