11C MOLLUSCA OF THE GREAT OOLITE OF YORKSHIRE. 



costulis transverse densest r iatis ; basi subconvexd dense costulatd et concentric^ striata ; 

 umbilico nullo. 



Shell conical, but depressed ; whorls (4 — 5) flattened, encircled with closely-arranged, 

 nearly equal rounded ribs ; the ribs are densely striated longitudinally ; the base is rather 

 convex, having very closely-arranged costae, crossed by concentric stria? ; no umbilicus. 



The junctions of the whorls are rather obscurely marked, and the lower margin of the 

 last whorl is angulated. The little ribs upon the base are very delicate and fine ; the outer 

 lip is imperfect, and does not enable us to describe the aperture ; but there is nothing 

 visible upon the surface of the whorls which would indicate that it belongs to Pleurotomaria. 

 The height is two thirds of the basal diameter. 



Locality. Scarborough. In Mr. Leckenby's cabinet. 



Trochus monilitectus, Phil. Plate XV, figs. 1, la. 



Trochus monilitectus, Phil. 1835. Geol. of York., vol. i, t. 9, fig. 33. 

 — — . jyOrb. Prod. Paleont., p. 2G5. 



T. Testa conicd, anfractibus (8) plants, suturis obscuris 4 — 5 costatis ; costis crebris 

 oblique crenulatis. 



Shell conical, volutions (8) flattened, with indistinct sutures, and encircled with 4 — 5 

 rows of costae ; the costae are closely arranged, and crenated obliquely. 



The costae are large, the crenations closely arranged, and pass obliquely from left to 

 right. Length 4^ lines, basal diameter 3| lines. 



Locality. Near Scarborough. The original specimen figured by Phillips. 



Turbo elaboratus, Bean. Plate XV, fig. 2, 2a; and Plate IX, figs. 27, var. 



Turbo elaboratus, Lycett. 1850. An. Nat. Hist., vol. vi, p. 41G, pi. 11, fig. 1. 



T. Testa subturritd, apice acuto, anfractibus (4) subconvewis, superne plants, in/erne 

 costulis longitudinalibus numerosis, aliis transversis decussantibus ; anfractu ultimo ventricoso 

 obliquo, aperturd ovafd. 



Shell turreted, apex acute, whorls (4) convex, their upper borders flattened horizontally, 

 their sides and lower portions, with numerous longitudinal ribs, transversely decussated 

 by others ; last whorl oblique ; aperture entire, ovate. 



The longitudinal ribs are rendered nodulous by those which are transverse ; the latter 

 are 4 or 5 in number; the last volution has numerous encircling ribs, but the longitudinal 

 ones do not extend beyond the middle of the volution ; and when more than four whorls 

 have been completed, the last whorl is destitute of longitudinal ribs, but in lieu of them are 



