PLEUROTOMARIA. 441 



Description : 



Height (elevated variety) . . .28 mm. 



Basal diameter . . . .40 mm. 



Spiral angle ..... 95°. 



Shell conical-depressed, slightly umbilicated. Spire regular and sharp, the 

 angle ranging from 95° to about 110°. Whorls (seven) flat and sloping, with a 

 close suture which is scarcely canaliculate. The ornamentation is granulated 

 throughout, a feature arising from an elevated decussation of the spiral and radial 

 lines. A belt which is studded with a kind of triple tuberculation forms the base 

 of each whorl, but the ornaments of this belt are subject to modification, and its 

 character is sometimes changed owing to the undercutting of the whorls. 



The sinus-band is anterior, round, and prominent, but not wide. In the earlier 

 stages are spiral lines decussated, but in the later stages the growth-lines alone 

 are seen, very closely packed (PI. XL, fig. 1). The body-whorl is relatively large 

 with granulate ornament and a blunt belt, or basal carina, richly granulated or 

 tuberculated, these tuberculations losing their sharpness towards the anterior 

 extremity. Base convex, with spiral ornamentation rather faint, generally 

 wanting in the middle portion of the base, though the radial lines are pretty 

 strong. Umbilicus rather small, and inclined to be funnel-shaped. Aperture 

 subrhomboidal. 



Relations and Distribution. — Originally described from Dundry, PI. granulata 

 swarms in the Sauzei-bed at Oborne and other localities in the Sherborne district. 

 There is a wide-angled variety from Milborne Wick (XXXIX, 10) which, to a 

 certain extent, prefigures forms that are characteristic of the Parkinsoni-zone, 

 e. (j. PI. Palsenwio. 



382. Pleurotomaria phylax, sp. nov. Plate XL, figs. 4«, -ib, 4 c. 



This rather curious shell is found rarely in the Sauzei-hed at Oborne, and may 

 be a sport or megalomorph of the more depressed variety of PL granulata. The 

 sinus-band, however, presents considerable differences. 

 Description : 



Height . . . . .25 mm. 



Basal diameter . . . .44 mm. 



Spiral angle . . . . .115°. 



Shell conical-depressed, thick, slightly umbilicate. Spire rather convex with 



a very obtuse apex. Whorls (six) sloping regularly to the basal carina, which in 



some cases is rather undercut. The spiral ornamentation is delicate and regular 



