96 GASTEROPODA OF THE INFERIOR OOLITE. 
from D’Orbigny’s description), and where this is not so, it would seem to be the 
result of wear. The spirals are often faint, except in the lower part of the body- 
whorl, where they are more prominent ; but thereis much variation in this respect. 
On the whole, the spirals are fewer and stronger in the anterior than in the 
posterior area of each whorl, and in well preserved specimens are seen to be 
decussated with fine longitudinal striz. 
Aperture subquadrate, inclining to rhomboidal; columella scarcely reflexed ; 
anterior groove more marked in some specimens than in others. Umbilical slit 
variable. 
Relations and Distributions.—The forms described below, viz. P. “ fusiformis”’ 
and P. carino-crenata, are probably nothing more than varieties of the somewhat 
variable species identified as P. bianor. But this section of the genus Purpuwrina, 
as was noticed by Hébert and Deslongchamps in dealing with P. granulata, recalls 
the form of Amberleya (Hucyclus) with considerable force. It will be remembered 
that many species of eucycloid Purpurine were figured by D’Orbigny in the ‘ Ter- 
raines Jurassiques,’ e.g. P. ornata, P. bathis, P. belia. Forms greatly resembling 
these our paleontologists have hitherto treated as belonging to the genus Amberleya. 
Itis difficult to say where the line should be drawn, since many of the shells referred 
to Amberleya show considerable anterior grooving when well preserved. Alto- 
gether, the section of Purpwrina which contains P. bianor is anomalous, and full 
of difficulty, as we shall perceive in the sequel. 
In this country P. bianor is essentially a fossil of the Parkinsoni-zone, being 
fairly abundant in P,, Burton Bradstock Cliff, and in the same horizon at Vitney 
Cross, and Upper Loders. In North Dorset it occurs sparingly in the Parkinsoni- 
beds at Halfway House and Bradford Abbas. 
15. Purrurtna (EvucycLoipna): Species or Variety related to P. Branor. Plate II, 
figs. 6 a, b. 
This shell differs from the preceding in having asomewhat smaller spiral angle, 
and in its more fusiform outline. The body-whorl presents a distinctly defined base, 
and the anterior portion of the whorls of the spire has less of an inward slope ; 
consequently the whorls are less angular. The keels are richly crenulate; the 
spirals above the keel consist of a well-marked line near the suture, and two others 
which are fainter; the spirals below the keel are two in number and stronger ; all 
are finely decussated by axial striz. 
Aperture imperfect, but probably like the preceding. 
It is not impossible that this form may be a poor representative of Turbo sub- 
