258 E. Wilson — British Liassic Gasteropoda. 



III. — British Liassio GtAsteropoda. 

 By E. "Wilson, F.G.S. ; Curator of the Bristol Museum. 



{Concluded from p. 202.) 

 Cekithium trigemmatum, spec. nov. PI. V. Figs. 10, 10a. 



Description. — Shell conical, turrited ; apex acute ; spiral angle 

 regular, whorls 8-9, angularly carinated anteriorly; sutures wide 

 and deep ; each whorl bears 3 spiral rows of equally spaced but 

 unequal neatly rounded tubercles ; the anterior of these, which are 

 much the largest, are set on the carina ; the middle row consists of 

 fine granules, whilst the nodules of the posterior row, which adjoin 

 the posterior suture, are intermediate in size and half-way between 

 the other two. Fine, close-set curved strise of growth cross the 

 whorls transversely, but are scarcely discernible even with a lens, 

 except on the last whorl of well-preserved specimens. Last whorl 

 bicarinated by a fourth very finely granular raised line, between 

 which and the coarsely nodulated carina is a plain encircling thread ; 

 base flattish, bearing a few concentric raised lines. The aperture is 

 imperfect in all the specimens I have examined, but is roundly ovate 

 in form, and occasionally shows slight indications of the commence- 

 ment of an anterior canal. I therefore assign this species to the 

 genus Ceritliium. 



Dimensions. — Length, 7"o millimetres ; diameter, 2-5 mm. ; spiral 

 angle, 22° ; sutural angle, 97°. 



Geological Position and Locality. — Lower Lias, zone of Am. 

 oxynotus, Eailway-tunnel, Old Dalby, Leicestershire. 



ACT^ONINA FERREA, SpOC. UOV. PI. V. FigS. 11, 11a. 



Description. — Shell pyriform, smooth and shining ; spire depressed 

 near the shoulder of the last whorl, but presenting a small pyramidal 

 elevation in the centre ; this portion of the shell is badly preserved, 

 but the total number of the whorls appears to be 5 ; a narrow groove 

 encircles the shoulder of the last whorl above (posterior to) the 

 rectangulated keel. The aperture is almost entirely concealed in my 

 sole specimen, but it widens out somewhat towards the anterior 

 extremity, and the inner lip is thin with a sharp edge anteriorly, 

 vpithout any fold or thickening over the columellar region. A few 

 (5 or 6) fine encircling strige are discernible on the anterior portion 

 of the last whorl. 



Dimensions. — Length, 7*5 mm. ; diameter, 5 mm. ; length of last 

 whorl, 6*75 mm. 



Geological Position and Locality. — Middle Lias, Marlstone Eock, 

 zone of Am. spinatus, East Norton Embankment, derived from 

 Tilton, Leicestershire. 



Cylindrites ^qualis, spec. nov. PI. Y. Figs. 12, 12a. 



Description. — Shell ovately and regularly fusiform ; spire moderately 

 elevated, obtusely conical ; apex acute ; whorls 5, slightly convex, 

 embracing, with narrow ill-defined sutures. A narrow impressed line 



