100 GASTEROPODA OF THE INFERIOR OOLITE. 
more than one-third the size, is wider-angled, and has a flatter base ; the notch also 
is probably wider and more distinct. There is an undescribed species of Brachy- 
trema in the Bajocian of Normandy (for a specimen of which I am indebted to the 
generosity of M. Deslongchamps), which greatly resembles this form, and also B. 
Wrightit, but yet has points of difference from both. These differences are probably 
not more than varietal. B. Wrightii and its allies represent the group of Brachy- 
tremas which are related to Purpuroidea. In the well-preserved specimens of the 
French Bajocian it is possible to note this relationship. 
The variety despecta is founded on a unique specimen from P;, Vitney Cross 
(see p. 38), and is the only Brachytrema that has hitherto to my knowledge been 
found in the Inferior Oolite of England outside of the Lincolnshire Limestone. If 
additional evidence as to its differing materially from B. Wrightii should be 
obtained, the species may be known as BrachyrrEMA DESPECTUM. 
Famity APORRHAIDA. 
“ Shell turrited, aperture continued in front by an imperfect canal or a groove ; lip 
expanded, aliform or digitate.’’—Fiscuer. 
The Inferior Oolite, in England, contains three genera, which may be referred 
to this family, viz. Malaptera, Piette, Spinigera, D’Orbigny, and Alaria, Morris 
and Lycett. These genera are probably of unequal value, and it might perhaps be 
difficult to give a very rigorous and logical definition of any one of them, so linked 
are they to all appearance by connecting forms. Besides the three named genera 
there are one or two species of the Aporrhaide, which seem rather difficult to 
place under any of the above. 
The Cretaceous Aporrhaide have received a considerable amount of atten- 
tion from Mr. J. Starkie Gardner,'! and, in common with some other concho- 
logists, he failed to see any difference of generic value between Alaria and the 
existing Aporrhais. However, Fischer clearly endorses Piette’s view as to the 
propriety of keeping Aporrhais distinct from at least the bulk of the shells usually 
referred to Alaria ; and the farther we go back in time, the more the Alaria-group 
predominates over the others, until its origin is lost in the small and often obscure 
forms, which a minute and careful search is gradually revealing from the Lias. 
' “On the Gault and Cretaceous Aporrhaidm,” by J. Starkie Gardner, F.G.S., ‘ Geological 
Magazine,’ 1875. 
