TROCHUS. 369 



rather than by identical forms of the Granata-grouip ; although, here and there, as 

 in the " Base-bed at Lincoln and also at Leckhampton, there are micromorphs 

 which may be taken to represent this species. In my own collection " D. granata, 

 var.," stands for certain forms of this group. One of the most beautiful of these, 

 apparently between D. angulata and D. granata, was found by Mr. Wilson in the 

 Inferior Oolite, " Juniper, Painswick." 



305. Delphinula (Turbo) Santonis, sp. nov. Plate XXX, figs. 18, 18 a. 



Description : 



Height . . . . .9 mm. 



Width . . . . .9 mm. 



Shell conical, turbinate, umbilicated. Spire elevated, spiral angle rather obtuse 

 (about 68°) ; apex smooth. Number of whorls five, slightly carinated, the orna- 

 ments consisted of deep-cut granulated spirals, with one median spiral of moderate 

 prominence, situate at the angle of the whorl ; sutures slightly canaliculate. 



The body-whorl is full and rounded ; it carries three granulated spirals 

 posterior to the keel which is merely indicated by a spiral of larger granulations ; 

 below this are two granulated spirals rather more wide apart. The base is full 

 and richly decussated by fine spiral and radial lines, collected into a frill at the 

 margin of the variable umbilicus. Aperture suborbicular, with a slight thickening 

 of the inner lip. 



Relations and Distribution. — Notwithstanding its narrower spire, smooth 

 outlines, and Turbo-like character, this form must, I think, be classed with the 

 Granata-grovap, and more especially with D. granata. There are three specimens 

 in the Jermyn Street Museum from Santon, in North Lincolnshire. 



Genus — Trochus, Linnseus, 1758. 



Shell conical with an elevated spire, whorls numerous, but slightly convex ; spire 

 somewhat pointed ; last whorl heeled or angular; base concave, flattened or slightly 

 convex ; aperture rhomboidal ; lip sharp, very oblique ; columella curved, more or 

 less prominent at its union with the outer lip. 



The species from the Inferior Oolite classed below under Trochus answer 

 fairly to the above diagnosis, though presenting considerable differences amongst 

 themselves. They may be roughly separated into three divisions. 



