W. R. EucUeston — On the Yorkshire Oolites. 155 



1848. Plcurotomaria undosa, Deslongcli., Mem. Soc. Linn. Norm. vol. viii. p. 77, 



pi. 12, fig. 2. Upper Lias. 



1849. Pleurotomaria cinglica, D'Orbigny, Prod. i. p. 214. Et. Sinem. 



1854. FUurotomaria anglica, Sow., Morr. Cat. p. 271. Lias ; Yorkshire, Somerset. 

 1876. Fieurotomaria undosa, Sow., Tate and Blake, p. 339, pi. 9, fig. 1. Mid. Lias. 



Bihliogra2?Jiy, etc. — Since this is essentially a Liassic rather than 

 an Oolitic species, I feel scarcely justified in criticizing the literature. 

 The Dogger fossil is not unlike Sowerby's type ; but if there is 

 a difference, it leans perhaps more to the undosa variety. Sowerby 

 says that Lister found Pi. anglica at Bugthorpe, in Yorkshire, and 

 figured it in his Conchologj^ 



Description. — Specimen from the Dogger (zone 1), Peak (Blue 

 Wyke). York Museum. 



t Height 60 millimetres. 



Approximate ( Width 56 , , 



( Spiral angle 75°. 



Shell of large habit, trochiform, strongly turrited : height and 

 ■width nearly equal. Whorls about 8, increasing by steps within 

 a tolerably regular angle. The carina is situated towards the upper 

 part : it is coarsely tuberculated, the tubercles being depressed and 

 drawn out spirally : the entire shell seems to have been pervaded by 

 a system of fine spiral lines. 



The band of the sinus is very conspicuoiis in the body-whorl, and 

 is situated rather less than half-way between the carina and the 

 margin of the base. It constitutes a slight prominence, and seems 

 to show the " three central stris " mentioned by Sowerby in his 

 diagnosis. 



Belafions and Distribution. — Owing to the imperfect condition of 

 the shell, an absolutely correct identification of the Dogger fossil 

 with this or that member of the anglica-grovi'p is almost impossible. 

 It comes very near PI. araneosa, Desl. (cf. D'Orb. T.J. p. 416, 

 pi. 352, figs. 5-9), a Middle Lias species, but in that one the band of 

 the sinus is in a slight depression, whereas in our shell it occupies 

 a slight prominence. The large Pleurotomarice of the French Eajocian 

 are all different from this one, and so are those of Dorset-Somerset 

 as far as my knowledge extends. 



The highly ferruginous matrix and other indications convince me 

 that the specimen figured belongs to the Dogger proper, and not to 

 the Dogger Sands. But a specimen was found lately by Mr. Walter 

 Keeping, which I understood him to say had been obtained from the 

 sands that carry the Dogger. There are three specimens in the York 

 Museum. I know of none others from this horizon.* 



* 1. There is nothing absolutely exceptional in the reappearance of Liassic forms in 

 the Inferior Oolite. We have a remarkable instance of this in the presence of large 

 specimens of Awmonites Jimbriatus in the Sutnphresianus-hed at Oborne, near 

 Sherborne. In that case there can be no doubt that a few individuals of Am. 

 JiiiibriaiuK lived to witness the reign of the coronati. 



2. There are two species of Pleurotomaria^ in addition to the four already 

 detailed by me, included in the list of the " Geology of Yorkshire " (3rd ed. p. 259), 

 of whose title to be regarded as Yorkshire fossils I can find no evidence. These are : 



Phurotomaria bicarinata, Sow., t. 221. Calc. Grit, Gristhorpe. 



Pleurotomaria cingulata, Phil. Calc. Grit, Scarborough. 



