PURPURINA (EUCYCLOIDEA). 95 



Section II. — Pckpurina, Auctorum nonnullorum. 



A considerable modification in the diagnosis of the genus is required to 

 admit the following species ; where the spire is longer, the body-whorl less tumid, 

 and the whole shell angular and eucycloid. Indeed, I should prefer to distinguish 

 this group as Eucycloidea — small shells with carinated whorls ; carinas median and 

 crenulate ; aperture rhomboidal, with a short and narrow anterior canaliculation. 



14. Purpurina (Eucycloidea) bianor, D'Orbigny, 1850. Plate II, figs. 5 a, b, c ; 



5 d, e; 5/, g, h. 



1850. Tuebo bianor, WOrbigny. Prod. 1, fit. 10, p. 266. 



1852. Purpurina bianor, VOrbigny. Ter. Jur. 2, pi. 331, figs. 14, 15. 



1860. Cf. also Purpurina granulata, Eeb. and Best. Poss. de Montreuil- 



Bellay, p. 28, pi. 7, 

 fig. 9. 



Bibliography, Sfc. — I can find no adequate description of P. bianor. In the 

 Prodrome, D'Orbigny merely says that T. bianor is near to T. belia, but more 

 elongate, more carinate in the middle of the whorls, and without crenulations. 

 Occurs at Port-en-Bessin. In the ' Terrains Jurassiques' no text accompanies the 

 figure of P. bianor. On the other hand, our shell greatly resembles specimens from 

 Normandy, which Prof. Deslongchamps and other palaeontologists refer without 

 hesitation to P. Manor, D'Orb. These occur in the beds of Bayeux. 



P. granulata, H. and D., greatly resembles some of the larger specimens from 

 Vitney Cross, but on the whole the ornamentation of P. granulata is richer, 

 especially on the carinas. But if the Vitney Cross specimens were as well preserved 

 as those from the Callovian of Montreuil-Bellay, it might, perhaps, be more difficult 

 to indicate the difference. 



Description : 



Length of a well-grown shell . . .13 mm. 



Ratio of width to length . . . 65 : 100. 



Length of body- whorl to entire shell . . 55 : 100. 



Spiral angle .... 55°. 



Shell conical, eucycloid ; spire nearly half the length of the shell, apex sharp. 

 Whorls about seven in well-grown specimens, very angular, having a strong keel, 

 which is median in the whorls of the spire ; body- whorl with one strong keel, and 

 showing no distinctive base. The keels are regularly and finely crenulate (differing 



