220 PLIOCENE MOLLUSCA. 



1875. Plevrotoma Brocchii, Seguenza, Boll. R. Com. Geol. Italia, vol. vi, jj. 206, no. 147. 

 1877. Drillia Brocchii, Bellardi, Moll. Terr. Terz. Piem., pt. ii, p. 101, pi. iii, fig. 26. 

 1890. Drillia (Crassispira) Brocchii, Sacco, Boll. Soc. Geol. Ital., vol. ix, p. 270, no. 4014. 



Specific Characters. — Shell thick and strong, turreted ; whorls channelled near 

 the centre, the channels being wide bnt not deep ; ornamented by fine undulating 

 spiral stride, stronger and more distant on the lower part and on the back of the 

 body-whorl, and by about ten obtuse and oblique longitudinal costas, not very 

 prominent, which do not reach the base of the shell, with wide spaces between 

 them ; suture slight ; mouth oval, slightly expanded al)Ove, narrowing towards the 

 canal, which is straight and very short. 



Dimensions. — (Of Crag specimens) L. 20 mm. B. 7 mm. 



Distribution. — Not known living. 



Fossil : Waltonian Crag : Beaumont, Little Oakley (probably 

 derivative). 



Miocene : Touraine. Upper Pliocene : France — Biot ; Italy — Asti, Bologna, 

 Livorno. 



Reinarhs. — The Drillias are a group of the Pleurotomida^ having a turriculate 

 spire, a comparatively short body-whorl and a short and recurved canal ; the 

 inner lip is generally thickened, the outer lip reflexed, with a well-marked labial 

 sinus and sometimes a pad-like swelling near the suture. 



I have found several shells at Beaumont and Oakley, more or less imperfect, 

 vmlike anything hitherto reported from the English Crag. Submitting them to my 

 friend Prof. Sacco, of Turin, he was kind enough to send me a specimen of Drillia 

 Brocchii from the Upper Pliocene of Piedmont, to which species he thinks they 

 may be referred. My fossils are somewhat smaller, but probably do not differ 

 from the type form more than might be expected considering that they lived in 

 areas so widely apart. From their appearance I should conclude they are 

 derivative in the Crag. The study of such derivative forms is important, as it 

 may enable us to form a better idea as to the general character of the well-nigh lost 

 molluscan fauna of the North Sea region during the Miocene and older Pliocene 

 epochs. 



Drillia icenorum (S. V. Wood). Plate XXVII, figs. 16, 17. 



1848. Pleurotoma semicolon ?, S. V. Wood, Mon. Crag Moll., pt. i, p. 54, pi. vi, fig. 3 a. 

 1879. Pleurotoma icenorum, S. V. Wood, Mon. Crag Mull., 2nd Supi>l., p. 19, pi. iii, fig. 8. 



Specific Characters. — Shell strong, ovato-elongate ; whorls 7, convex, carinated, 

 regularly diminishing in size, the last much the largest, less than half the total 

 length ; ornamented by a single row of prominent rounded nodules on the keel, and 

 by well-marked spiral ridges below it, especially on the body-whorl ; apex blunt ; 



