TROCHUS PDOMATUS. 91 



with lines of growth. The base is much swollen, and shows only the smallest relics 

 of spiral lines near the band, but is deeply scored by the lines of growth. From 

 Scarborough. In the Sedgwick Museum. 



Description. — The strength of the basal belts varies in different individuals, and 

 in the roughest they are very conspicuous. Their prominence makes the whorl 

 surface between them look concave. 



Distribution and Relations. — All these specimens, perhaps twelve, are from 

 Scarborough. Although this is a near ally of T. strigosus, being made of the 

 same elements differently proportioned, the association of these proportions is so 

 constant that the}' seem to have greater significance; one always seems to carry 

 the rest with it. If there is a swollen posterior spiral, or a very convex base or 

 very slight signs of any spirals on it, there is sure to be a prominent basal band 

 with a furrow above it on the sides of the whorl, and usually a furrow below it 

 on the base. These features should be recognisable if the species is found any- 

 where abroad. 



Trochus shiptonensis, sp. nov. Plate VIII, fig. 20. 



Type. — Length 11 mm., greatest breadth 9'5 mm., spiral angle 52°, whorls 6, 

 surface conical, sutures not much impressed. Basal edge angular, somewhat turned 

 up, bevelled below. Upper surface of whorl concave, forming a narrow furrow 

 anteriorly, then three narrow simple spirals posteriorly with oblique shallow 

 risings, sloping away from the aperture. Base, within the level, quite smooth, 

 with a central depression but no umbilicus ; aperture broken off. Shell thick, inner 

 tube uniformly oval. From Shipton-on-Cherwell. In the collection of Mr. 

 Hudleston. 



Distribution and Relations. — Only one of these has been examined, and the 

 matrix enclosed seems almost too white for Cornbrash at this spot, so it may 

 possibly come from one of the underlying limestones. It appears, however, to 

 belong by its shape and ornament to the same series as the above, which, never- 

 theless, are not confined to the Cornbrash, though apparently somewhat charac- 

 teristic of it. 



Trochus ?domatus, sp. nov. Plate VIII, fig. 22. 



Type. — Height 7'5 mm., maximum breadth 8 mm., whorls 3, forming a dome- 

 like spire. The last whorl lias a convex centre with a keel above and below 

 separated by a depression. No minor ornaments whatever. The base is separated 

 l»\ a strong smooth keel slightly separated below. The rest is smooth and convex, 



