468 GASTEROPODA OF THE INFERIOR OOLITE. 
The figured specimen has the following dimensions :—Height 10 mm., spiral 
angle 45°. The number of whorls five ; aperture sub-elongate, elliptical, with a short 
columella, which has folds and anterior notch somewhat reflexed. 
Relations and Distribution.—Lycett’s type is smaller than the figured specimen, 
and ill-preserved, but there is sufficient of the aperture remaining to show that it 
belongs to this section of Actzon (Tornatellxa) : it was obtained from the Free- 
stones of the Cotteswolds—Murchisonx-zone. The figured specimen is a larger 
shell, and was obtained from Drympton (most probably Opalinus-zone). 
This species comes very near to Tornatellea inequistriata, Cossmann, from 
the Murchisone-zone of the Meurthe. 
Besides the three species of Actwon (Tornatellea) described above, there are 
two other species or varieties: viz. a form in the Opalinus-bed, Drympton, 
resembling but not identical with Actwon pulchellus; secondly the narrow form 
from the ** Base-bed,” Lincoln, provisionally classed with Actzon ooliticus. 
Genus—Actmonina, d’ Orbigny, 1850 (= Orthostoma, Deshayes). 
“ Shell oval or fusiform ; spire salient, but shorter than the last whorl, which is 
angular in the vicinity of the suture ; aperture elongated, narrow, entire, not sinuous ; 
outer lip simple, sharp; columellar lip curved; columella thick, but smooth.” — 
FISCHER. 
There is nothing in this diagnosis with reference to sculpture, but one might 
add “smooth or striated.” The above is a somrewhat generalised diagnosis, which 
would include the sections previously mentioned. 
The genus Acteonina is interesting to the paleontologist as perhaps the oldest 
member of the Tornatellidwe, the section, Cylindrobullina, dating back from 
Carboniferous times. It is best represented in the Jurassic period, and, according 
to d’Orbigny, the maximum development of the genus was attained during the 
deposition of the Lower Lias. As regards distribution in the Inferior Oolite of 
this country, the several horizons in Yorkshire have yielded a considerable 
number of species, the Lincolnshire Limestone and the Inferior Oolite of the 
Cotteswolds are also accountable for several species, whilst the Dorsetshire beds, 
usually so rich in Gasteropods, have not yielded many species of Actwonina, 
We may admit that Actwonina is an inconveniently large genus, including 
forms of somewhat diverse character, both as to shape and ornamentation. As 
regards ornamentation merely, we might divide the Acteoninas of the Inferior 
Oolite into three groups: 
1. Acteonine with deep spiral grooving and a general resemblance to Actewon 
