124 W. H. Eudleston—On the Yorkshire Oolites. 



strigosiis, but besides being smaller (the figure of T. Scarhurgemsis 

 in Plate III. is enlarged, whereas those of T. strigosus are natural 

 size), the spiral angle is wider, the tuberculalions are finer and 

 sharper, and the whorls of the spire are devoid of the basal belt, 

 which is seen in most siDecimens of T. strigosus, and which occa- 

 sionally assume exaggerated dimensions (see Fig. 4). Nevertheless, 

 unless the specimens are well preserved, it is by no means easy 

 to distinguish in all cases whether some of the smaller specimens 

 referred to T. strigosus should not be placed here. On the other 

 hand, subsequent investigation may serve to show that T. Scarhur- 

 gensis is merely a variety of T. strigosus with a wider base, finer 

 ornaments, and with the whorls of the spire less exposed. 



76. — Trochus strigosus, Lycett, 1863. Plate III. Figs. 3, 3a, and 4. 

 1863. Trochus strigosus, Lycett, Suppl. Gt. Ool. Moll. p. 29, pi. 45, fig. 12. 



Bibliography, etc. — This species was described from a single 

 specimen, obtained in the Cornbrash of Gristhorpe Bay, in the 

 collection of Mr. Leckenby. 



Descriptions. — Specimen from the Cornbrash (zone 4). Leckenby 

 Collection. Type refigurbd. Figs. 3 and 3a. 



Height 23-5 millimetres. 



Width 20 „ 



Spiral angle 65°. 



Ratio of body- whorl 46:100. 



Shell conical, imperforate. Spire consists of about 5 or 6 whorls, 

 which are neai'ly flat, and separated by a tolerably close suture. 

 The ornaments consist of five spirals, of which the four posterior 

 ones are granulated and nearly equal : the fifth or anterior spiral 

 becomes a broad belt consisting of one row of fine granulations, and 

 two or three raised lines which are not granulated : the ornaments 

 of the body-whorl are similar in character, the basal belt being very 

 wide. (In other specimens the spaces between the spirals of the 

 body-whorl are striated obliquely to the axis. This feature is 

 perhaps more apparent in the worn than in the better preserved 

 specimens.) 



Base tumid, with a system of spiral lines or strige, which extend 

 well up to the columellar area, and are strongly decussated by radial 

 lines. Aperture subquadrate, and but slightly depressed. 



Another specimen. — Same horizon, locality, and collection. Fig. 4. 



Height 36-5 millimetres. 



Width 30 „ 



Spiral angle , 63°. 



Eatio of body-whorl 50 : 100. 



This is a rugose specimen where the features above described in 

 the type are exaggerated. The basal belt is greatly enlarged, and 

 projects so as to give the shell a sort of reversed turriting. 



Relations and Distribtition. — Somewhat more rugose and irregular 

 than either of the preceding species, with a larger habit of growth. 

 In T. strigosus the cone is less perfectly regular : moreover, the 

 basal belt in each whorl projects considerably, presenting a feature 

 the converse of that in T. Scarburgensis, where the salience is due to 



