84. GASTEROPODA OF THE INFERIOR OOLITE. 
very limited extent—by the whorls of the spire presenting longitudinal ribs more 
or less marked, cut by transverse striz, a strong keel, or at least a very pro- 
nounced ‘ressaut,’ forming upon the whorl a ‘meplat’ towards the suture, 
which is deeply cut; finally a body-whorl much more developed than the 
others.” 
It is somewhat difficult to understand on what grounds Fischer places this 
genus under the Littorinide, and yet in the so-called Purpwrina bianor and its 
allies there is a very strong resemblance to some sections of the numerously- 
represented genus Amberleya (Hucyclus). On the other hand, Amberleya ornata, 
D’Orb. (non Sow.), is very like a Purpurine, and was, in fact, recognised as such 
by Oppel (‘ Juraformation,’ p. 387), who records it from the Humphriesianns-zone 
of Oeschingen, and also from the Bayeux beds. In well-preserved specimens of 
Amberleya ornata, D’Orb., the anterior groove or incipient canal is as well marked 
as in most Purpurines, and better perhaps than in the majority of specimens 
obtained by collectors. Thus there is certainly a link between Pwrpwrina and 
Amberleya, though there may be no real affinity. Our difficulties are still further 
increased by the fact that Fischer classes Amberleya under the Turbinide. As 
regards the so-called canal in Purpwrina it may be seen to vary from a very strong 
and well-defined channel with reflexed columella, such as those of P. aspera 
(Pl. I, fig. 11) and P. calcar (PI. II, fig. 1), to the shallow, spoon-shaped grooves 
of P. bellona (Pl. I, fig. 5) and P. inflata (Pl. I, fig. 2). It should also be remem- 
bered that in the majority of specimens the anterior extremity has lost all original 
character from wear, so that we are only now and again permitted to see what the 
shell really was like. 
Distribution, §c.—The duration of the genus appears to have been limited. 
The oldest form known to us in England is P. ornatissima, Moore, said to occur 
in the Marlstone of [minster (Moore, ‘ Middle and Upper Lias of S.-W. England,’ 
p. 89, pl. v, figs. 20, 21), where it is described as being very rare. There is a 
somewhat similar form figured and described by Vacek (p. 53 (109), pl. 18, fig. 7) 
as P. bellona, D’Orb., from the opalinus-zone of the subalpine region. Nowhere 
are these pretty shells common, but in England they are the most abundant and 
best preserved in the Inferior Oolite of Dorsetshire, where the Parkinsoni-zone of 
Burton Bradstock yields for the most part different species to those characteristic 
of the Sowerbyi-bed of Bradford Abbas. 
In the Inferior Oolite of the Cotteswolds Purpurina is rare, and usually in 
such indifferent preservation that the finer distinctions, held to constitute specific 
differences, can scarcely be made out. The same remarks apply for the most 
part to the Lincolnshire Limestone and Yorkshire Dogger. On highér geological 
horizons in England one species of Purpwrina has been recognised in the Great, 
Oolite (Bathonian), and another species in the Cornbrash and Kelloway Rock of 
