92 GASTEROPODA OF THE INFERIOR OOLITE. 



strongly crenulate, keel of the body-whorl enormously so. Costse wide apart, 

 scarcely traceable anteriorly, but strongly developed below the keel, though dying 

 out towards the base of the shell. Spirals above the keel fine and numerous ; few 

 and wide apart (two or at most three) below the keel. The body-whorl, including 

 the base, has ten spirals. 



Aperture subquadrate with an extremely short columella, strongly reflexed, so 

 as to produce a notch of considerable depth. Hardly any trace of umbilicus. 



Relations and Distribution. — Evidently related to the last-named species, P. 

 calcar is extremely rare in the Sowerbyi~hed of Bradford Abbas. In this form we 

 perceive the coarsest ornamentation of any species of Purpurina known to me. 



Inflata Group. 



10. Purpitkina inflata, Tawney, 1850. Plate II, figs. 2 a, b, c ; 2 d, e ; 2/. 



1873. Purpurea inflata, Tawney. Dundry Gasteropoda, p. 4, pi. iii, fig. 9. 



Bibliography, fyc. — Mr. Tawney need not have apologised for making this 

 species, which is much nearer to P. Soiverbyi, Waagen, than to P. coronata, Heb. 

 and Desk, with which he tried to identify it. 



Description : 



Length of a well-grown shell . . .24 mm. 



Ratio of width to length . . . 80 : 100. 



Length of body-whorl to entire shell . . 72 : 100. 



Spiral angle .... 93°. 



Shell ovate-globose ; spire about three-tenths of the entire length. Whorls five 

 to six, tumid, but flattened posteriorly and markedly canaliculate. Body-whorl 

 much inflated. The longitudinals or costEe are numerous, regular, of moderate 

 force, and with a slight slope from left to right. On the shoulder of the whorls 

 each rib terminates in a slight spinous projection, forming a closely crenulated 

 keel ; the costa? extend about half way down the body-whorl. The spirals are fine, 

 numerous, and regular, but are not seen to extend over the flat area. 



Aperture ovate to semilunar, with a short and scarcely inflexed columella in 

 the more adult specimens. In younger specimens the anterior groove is better 

 marked, and the umbilical slit is also more apparent. 



Relations and Distribution. — This species may be regarded as typical of the more 

 globular forms of Purpurina, which are found both in the Inferior Oolite of the 

 Anglo-Norman basin, and also in the Callovian of Montreuil-Bellay. It is 

 undoubtedly near to P. Sowerbyi, Waagen, but rather more tabulate. 



