492 GASTEROPODA OF THE INFERIOR OOLITE. 
clathrata have already been partially indicated. Attention is also drawn, in 
the accompanying footnote, to another form, lately found in the Lias of Thorn- 
combe, which evidently belongs to the same group, though generically, or at least 
subgenerically, distinct.’ 
Chilodontoidea oolitica is a rare species, yet it occurs on the same horizon at 
four localities, viz. the Concavus-bed at Bradford Abbas and the Irony Nodule-bed 
of Burton Bradstock; also at Beaminster and Stoford. 
455. Fossarus (Covrsovya’) ooniricus, sp. nov. Plate XLII, fig. 17. 
Description : 
Height ; : ‘ 2 Semmes 
Body-whorl to total hoe : ; 5 7d INNO). 
Spiral angle . : «602: 
An ovate elongate shell with a ee spire aia few whorls, which are non- 
embracing. A very slight umbilical fissure. The entire shell is ornamented with 
strong spiral ribs, regular and equidistant. Aperture a lengthened oval, with an 
arched and crenulated outer lip, expanded anteriorly, and a long and almost 
straight columellar lip. ‘The entire peristome is thick. 
Relations and Distribution.—There is very little difference between this shell 
and the existing Oouthouya reticulata, A. Adams, from the China seas. The 
modern shell has a better developed umbilical fissure, and is rather smaller ; [sapis 
fenestrata, Carpenter, from the west coast of North America, is also very near. 
A single specimen from the Concavus-bed, Bradford Abbas. 
1 Jn order to find a place for the Lias shell, I propose to constitute the genus Wilsonia, thus 
named in honour of Edward Wilson, Esq., F.G.S., Curator of the Bristol Museum, who is our chief 
authority on the Gasteropoda of the Lias. The following is the diagnosis : 
Shell small, very thick, irregularly pupseform, imperforate, whorls increasing irregularly and scarcely 
convex, separated by a distinct but rather narrow suture. Ornaments pronounced, consisting of four or 
five granular spiral belts in each whorl, with fine intermediate axial decussation. Body-whorl rather 
shorter than the spire and compressed. Aperture sub-circular, with a thick outer lip and two prominent 
teeth towards the middle of the short columella. 
Wilsonia liassica, sp. nov. (Plate XLIV, figs. 134, 134, 13 ¢), has seven or eight whorls and a 
total height of about 14mm. ‘The prominence of the penult, which quite equals the body-whorl in 
width, is a characteristic feature; the ornamentation is very rich. A single specimen from the 
“junction-bed,’’ Thorncombe, Dorset. 
In Wilsonia the aperture possesses two distinct teeth: in Chilodontoidea there are three 
callosities or teeth, and the internal portion of the aperture thus assumes a somewhat keyhole- 
like shape: in Chilodonta the aperture is restricted by five irregular teeth, and thus becomes still 
more fanciful in outline. We can scarcely doubt that these three genera (or sections) stand in 
ancestral relationship to each other, either linear or collateral. 
2 Couthouya, A. Adams, 1860, sub-genus of Mossarus, Philippi, 1841, member of the Littorinide. 
Cf. also Fossariopsis, Laube, from the Trias. 
