196 E. Wilson — British Liassic Gasteropoda. 



For a full moiety of the material on whicli the following species are 

 founded I am indebted to Mr. W. D. Crick, of Northampton, who 

 has very generously placed a number of interesting specimens at my 

 disposal for the above purpose, and has also furnished me with much 

 valuable information as to their precise geological position. I am 

 under a considerable obligation to the Eev. H. H. Win wood, M.A., 

 F.G.S., for the facilities he has kindly given ma for examining the 

 specimens in the Bath Museum, to Mr. H, E. Quilter, of Leicester, 

 for assistance with specimens from that county, and to Mr. T. Beesley, 

 F.CS., of Banbui-y, and Mr. B. Thompson, F.G.S., of Northampton, 

 for useful information on the general subject. 



Note. — In the following descriptions, the " sutural angle " is the 

 greater angle which the suture makes with the side of the spire ; and 

 the "length of the last whorl" is measured axially, and posteriorly 

 when practicable, from the anterior extremity of the aperture to the 

 last preceding suture. 



Description of New Species. 



Tkochus Dalbiensis, spec. nov. PL V. Figs. 1, la, Ih, Ic. 



Description. — Shell conical, as broad as high ; imperforate ; spiral 

 angle concave, apex acute ; whorls 7, slightly concave, separated by 

 deep sutures, last whorl very large relatively, squai-ely angulated at 

 the periphery. The ornamentation of this very pretty little shell is 

 as follows : — Numerous slender radial cost^ commence close to the 

 posterior suture in a row of fine granulations, apparently formed at 

 the junctions of the costee with a fine encircling thread, and are 

 continued forwards rather obliquely across two rows of larger 

 rounded tubercles, similarly occurring at the decussations of the 

 costee with fine encircling threads ; these two granulated lines 

 occupy the anterior third of the whorls, and the anterior one of the 

 two, which is the most prominent, gives a distinct angulation thereto ; 

 from each of the tubercles of this anterior row two fine threads pass 

 downwards obliquely across the deep sutural groove, and terminate 

 in a finely-granulated encircling thread close to the anterior suture. 

 Base of shell almost flat, very slightly convex, with 12 or more very 

 finely-crenulated concentric threads, which are closer together towards 

 the centre and circumference, and wider apart in the intermediate 

 area. Aperture trapezoidal, transverse and oblique. Outer lip boldly 

 arched, inner lip almost straight and efi'use over the columellar border. 



Dimensions. — Length, 8 millimetres; diameter, 8 mm.; length 

 of last whorl, 5 mm.; spiral angle, 70°; sutural angle, 128°. 



Affinities. — This species is somewhat closely related to Tr. Thetis, 

 Miin. (Goldfuss, Petr. Germ. pi. 179, figs. 10a, h : and Plate V. 

 Figs. 2a, h, c). It differs therefrom by its finer ornamentation, the 

 double row of anterior tubercles, the fine granules over the suture, 

 and the more numerous concentric striae on the base, also by its 

 greater spiral angle, larger number of whorls, and more acuminate 

 apex. Judging by the specimens of this latter species found at 

 Dalby associated with the foregoing form, Miinster's figure [Joe. cit.) 

 errs in showing unduly straight costse, want of tubercles on the keel, 



