W. S. Sudleston — On the Yorkshire Oolites. 123 



specific importance. Bearing in mind the difficulties wliich are 

 caused by difference of matrix and status of the fossils, it cannot be 

 expected that identifications should be more than approximate, la 

 the Corallian of Yorkshire, i.e. in the Coral Eag of Ayton and the 

 Coralline Oolite of Pickering, this section of Trochiis is represented 

 by T. Aytonensis, Bl. and H. (see Cor. Gast. Geol. Mag. 1881, PI. III. 

 Fig. 12). This is a still smaller species, with a wider spiral angle, 

 having three tuberculated spirals, the nodes in the uppermost one 

 being the strongest : moreover, the basal belt is more prominent in 

 the Corallian species. 



T. moniHtectus has never, to my knowledge, been found in the 

 Yorkshire Dogger. It is quoted by Brauns from three horizons of 

 the Middle Jura in N.W. Germany. But judging from the synonyms 

 which he gives, this identification must be received with caution. 



75. — Trochus Soarburgensis, sp.n.^ Plate III. Figs. 2, 2a. 

 Description. — Specimen from the Cornbrash (zone 4), Scarborough. 

 Leckenby Collection. 



Height 17'5 millimetres. 



Width 15 



Spiral angle 70°. 



Eatio of body-whorl 52 : 100. 



Shell conical, imperforate, slightly turrited : spire consists of about 

 six whorls, which are perfectly flat : suture close, sutunil line 

 but little inclined. The angle of increase is extremely regular, 

 and each whorl is ornamented by five richly cut tuberculated spirals, 

 with interspaces about 1^ times the breadth of each spiral : in the 

 body- whorl these interspaces are both relatively and actually- wider, 

 and are striated obliquely to the axis, i.e. from left to right. The 

 tubercles are small and globular, but become more irregular and 

 extended in the spirals of the body-whorl. 



The posterior spiral in each whorl is slightly the most prominent, 

 standing forward distinctly from the base of the preceding whorl, 

 so as to produce a slight tabulation. In the body- whorl the lowest, 

 or fifth spiral is supplemented by fine undulating lines, the whole 

 forming a broad belt which margins the base. This is tumid, and 

 ornamented with spiral lines or stride, slightlj' decussated by radial 

 lines : the spiral striee are not continued into the columellar area, 

 which is very thick and solid. Aperture subquadrate, and but little 

 depressed. Other indications wanting. 



Relations and Distribution. — This very pretty and regular Trochns 

 is distinguished from T. monilitectiis by its larger habit of growth 

 and wider spiral angle, by the slightly tabulate character of each, 

 whorl, and by the greater space between, the spirals : also by the 

 relatively shorter spire. It has closer affinities with Troclius 



1 This specimen is in a small tray mounted on a tablet in the Woodwardian 

 Museum. The tablet is labelled •' Trochus, Cornbrash, Scarbro'." The tray also 

 contiiins a MS. note, apparently in the handwriting of the late Dr. Lycett, which 

 runs thus : " A (?) Fistulana figured by Deslougch. from the For. Marble of 

 Langrune is probably the same as your rare Cornbrash one.'' At present 1 have not 

 been able to ascertain what reference is here intended. One rarely gets a fossil in 

 such good preservation as this : hence, 1 have ventured to distinguish it. 



