﻿PROSOBRANCHIATA. 



275 



No. 199. Pleurotoma Volgeri. Phil. Tab. XXX, fig. 13, a, b. 



Pleurotoma Volgeri. Philllpi. 1846. (Tert. Foss. Magdeb.) Paleontogr., vol. i, p. 69; 



t. 10 a, fig. 2. 



— — Morris. 1854. Cat. Brit. Foss., p. 271. 



P. testa gracilis fusif or mi, turritd, tuberculoid : spird acuminata: anfractibus convexis, 

 ad humcros cari?iam acutam, serie tuberculorum dentiformium instructam, gerentibus ; 

 inarginibus posticis latis, concavis, lacissimis ; ultimo anfractu piluribus lineis spiralibus 

 Jiliformibus, irregularibus, cincto, antice repente coarctato, in canalem Ion gum producto: 

 aperturd ovali ; labro leviter arcuato ; sinu latissimo, sub-prof undo, triangulari, ad carinam 

 collocato. 



Shell slender, fusiform, turreted, tuberculated ; spire pointed, elevated, nearly 

 as long as the aperture : whorls, six or seven, exclusive of the pullus, convex, sharply 

 carinated at the shoulders ; keel prominent, armed with a single row of rather closely 

 set, small, tooth-like tubercles; the posterior margins wide, concave, and very 

 smooth ; the last whorl, which is ornamented over the middle with several thread- 

 like, moderately distant, and nearly equal, raised, concentric lines, is contracted 

 suddenly towards the front, and produced into a long, straight, and rather wide canal. 

 The aperture is oval, the outer lip slightly arched, and the sinus, which is placed 

 on the keel, is very wide, moderately deep, and triangular in form. 



In the English specimens, the spire is rather more slender than that of the 

 specimen figured and described by Philippi, and the spiral lines on the last whorl are 

 nearly equal ; in all other respects the two shells agree perfectly. 



Size. — Axis, 7- 1 2ths of an inch nearly (14 millim.) ; diameter, rather more than 

 2-12ths of an inch (5 millim.) 



Localities. — Potter's Bar, where this pretty species appears to be very rare. 

 Philippi's specimen is from the neighbourhood of Magdeburg; but the precise locality 

 is not known. 



No. 200. Pleurotoma Waterkeynii. Nyst. Tab. XXX, fig. 8. 



Pleurotoma striatula. Be Kon. (non Buj.) 1837. Coq. foss. de Baesele, &c, p. 27, 



No. 28, t. i, fig. 6. 



— Waterkeynii. Nyst. 1843. Bull. Soc. Geol. de France, vol. xiv, p. 454, No. 29. 

 ;. — — Nyst. 1843. Coq., &c.,foss. de Belgique, p. 518, t. 41, fig. 4. 



— striatula. Bronn. 1848. Index Palseont., p. 1010. 



— Waterkeynii. B'Orb. 1852. Prod, de Paleontol, 26' Etage, No. 195, k. 



P. testa elongatd, sub-turritd, undique concentrice lincatd : spird elevatd, acuta : 



