80 GASTEROPODA OF THE INFERIOR OOLITE. 



collection at the British Museum. Beyond the fact that it is a Purpurina very 

 little else can be made out. 



Morris and Lycett observe that P. elaborata has likewise been obtained from 

 the Inferior Oolite (middle division) of the Minchinhampton district (p. 64), where 

 specimens are said to be larger and more satisfactory (p. 117) than those from 

 Scarborough. It has not been my lot to see any of these, though there are 

 specimens of Purpurina from the Oolite-Marl devoid of any very distinctive 

 features. Those authors speak of this species (p. 64) as occurring in the Inferior 

 Oolite of Normandy, an allusion probably to P. bellona, which occurs on a higher 

 horizon. On the whole P. elaborata must be regarded as a generalised form, 

 which disputes with P. bellona the title to rank as the representative of the genus. 

 In describing the really beautiful shells from the Sowerbyi-bed of Bradford Abbas 

 under this title I have endeavoured to utilise an old name rather than invent a 

 new one. 



Description : 



Length of a well-grown shell . . 20 mm. 



Ratio of width to length . . .75: 100. 



Length of body-whorl to entire shell . . . 66 : 100. 



Spiral angle .... 76°. 



Shell ovate-conoidal, apex acute. Whorls about five or six; posterior area 

 tabulate, sides moderately tumid. The ornaments consist of about eighteen stout 

 longitudinal costse, which are feebly developed on the tabular area, rise up into 

 spinous nodes on the keel, and are strong and regular in the flanks of the whorls. 

 The costee have a tendency to die out anteriorly on the body-whorl, a feature by 

 no means confined to this species. The costas decussate with regular and closely- 

 set spirals, which extend down to the base of the shell ; no spirals are seen on the 

 flat area. 



Aperture oval to subquadrate. Columella moderately reflexed so as to produce 

 anteriorly a wide and shallow groove towards the point. Umbilical slit scarcely 

 indicated. 



Relations and Distribution. — The group of the Purpurinas to which P. elaborata 

 belongs presents many features in common, and there can be no doubt that the 

 several species run into each other to a very great extent. In fact, according to 

 a lumping view of the case we might regard P. elaborata-bellona as one widely 

 distributed species characteristic of the Inferior Oolite, and also represented in the 

 Great Oolite of this country. When a badly preserved specimen turns up little 

 more can be done than refer it thus. There is no doubt, however, that average 

 specimens of D'Orbigny's P. bellona, which is fairly abundant in the " Oolithe 

 ferrugineuse " of Normandy, present characters which on the whole differ con- 

 stantly from average specimens obtained in the lower zones of the Inferior Oolite 



