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. 



Belations 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 Actseon {Tornatellaea) : it was obtained from the Free- 

 stones of the Cotteswolds — Marchisonx-zone. The figured specimen is a larger 

 shell, and was obtained from Drympton (most probably OjjaUniis-zoue). 



This species comes very near to Tornatellasa insequistriata, Cossmann, from 

 the Murchisonse-zone of the Meurthe, 



Besides the three species of Actseon {Tornatellsea) described above, there are 

 two other species or varieties : viz. a form in the Ojja/mns-bed, Drympton, 

 resembling but not identical with Actseon ]julchellus ; secondly the narrow form 

 from the " Base-bed," Lincoln, provisionally classed with Actseon ooUticus. 



Genus — AcTjEONINA, cVOrblgni/, 1850 (= Ortho.^toma, Deshayes). 



"Shell oval or fusiform ; spire salient, hut sJiorter than the last whovl, lohich is 

 angular in the vicinity of the sutiire ; aperture elongated, narrow, entire, not sinuous; 

 outer lip simple, sharp; columellar lip curved; columella thick, hut smooth.'^ — 

 Fischer. 



There is nothing in this diagnosis with reference to sculpture, but one might 

 add " smooth or striated." The above is a somewhat generalised diagnosis, which 

 would include the sections previously mentioned. 



The genus Actseonina is interesting to the palaeontologist as perhaps the oldest 

 member of the Tornatellidce, the section, GylindrohulUna, 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 Actseonina. 



We may admit that Actseonina is an inconveniently large genus, includiug 

 forms of somewhat diverse character, both as to shape and ornamentation. As 

 regards ornamentation merely, we might divide the Actseoninas of the Inferior 

 Oolite into three groups : 



1. Actseoninse with deep spiral grooving and a general resemblance to Actseon 



