384 GASTEROPODA OF THE INFERIOR OOLITE. 



Shell regularly conical, imperforate. Spire acute and about two-thirds the total 

 height. Number of whorls seven, flat or very slightly concave, sutures distinct ; 

 apical whorls smooth ; in the later whorls a fine unornamented spiral belt bounds 

 the anterior margin of each whorl ; sinuous growth lines are conspicuous 

 throughout. In the body-whorl these lines start from a granular spiral belt, 

 situate at the posterior margin, and extend to the basal angle, which is sharply 

 defined. Base rather flat and smooth; aperture subquadrate. 



Relations and Distribution. — The Weldon fossil differs from T. Dunlceri, of the 

 Great Oolite, in the plain anterior belt at the base of each whorl, in this respect 

 resembling Trochus Actsea, d'Orb. But other considerations prevent us from 

 regarding it as identical with d'Orbigny's species. This is undoubtedly very near 

 to T. Dunkeri, but even the rolling to which the Minchinhampton shells have been 

 subject could scarcely have obliterated the belt entirely. The other differences 

 might be fairly accounted for by difference of matrix. 



There are many varieties of Trochus Weldonis, connecting with other forms. 

 Common in the Lincolnshire Limestone at Weldon. 



323. Trochus substrigosds, sp. nov. Plate XXXII, fig. 11, and ? fig. 4 (incomplete). 



But cf. Tbochus acanthus, d'Orbigny. Terr. Jur., vol. ii, p. 273, pi. cccxii, 



figs. 9—12. 



— stbigosus, Lycett. Suppl., p. 29, pi. xlv, fig. 12. 



— acanthus, d'Orb. Cossmann, Et. Bath., p. 286, pi. x, figs. 27, 28. 



N.B. — Although T. acanthus, d'Orb., is a fossil of Port-en-Bessin, and 

 consequently belonging to the true Bajocian or Upper Division of the Inferior 

 Oolite, our fossils differ so much from d'Orbigny's figures that I scarcely dare 

 venture on absolute identification. On the other hand, there is a considerable 

 resemblance between our fossils and T. strigosus, Lycett, from the Yorkshire 

 Cornbrash. Now M. Cossmann, loc. cit., observes that, even supposing T. strigosus 

 is not an actual synonym of T. acanthus, the name is pre-occupied. The only way 

 out of these difficulties is to make a new species. 



Description (complete specimen) : 



Height . . . . .23 mm. 



Width . . . . .21 mm. 



Spiral angle ..... 60°. 



Shell conical, imperforate ; spiral angle tolerably regular. Spire rather more 

 than half the total height and acute. The total number of whorls is about eight ; 

 those of the spire (except close to the apex) are flat to very slightly concave, with 



