78 FAUNA OF THE CORNBRASH. 



front a concavity becomes produced on the surface, rising to and ended by the 

 angular edge which leaves a part of the base uncovered — so that there are two 

 keels. The aperture is oval and tolerably wide, with fair evidence of thickening 

 posteriorly where the callus is very prominent. The fine " growth-line " ornament 

 continues over all. The shell is so thick that the ridges make little show upon the 

 last. 



Distribution. — It has been thought that this species is peculiar to Scarborough, 

 and in fact forty-six specimens showing the shell have been collected ; but one has 

 also been obtained from Rushden, in a matrix resembling that of the locality, and 

 is now in the Northampton Museum. It is figured in PI. VIII, fig. 1. It must be by 

 casts that we may expect to recognise its presence elsewhere, and one of these, I 

 think there can be little doubt, is figured on PI. VIII, fig. 2, from Garsdon, near 

 Malmesbury. But there are other casts which cannot be referred to the same 

 species — some with too wide a spiral angle and some with too close a whorl. 

 These belong to species which have not been found in the shell, but only in 

 the cast. 



Relations. — This species is no doubt removed by small divergences from its repre- 

 sentative of the same group in other strata. But it is easily distinguished in the 

 adult, for in it the group rose to its acme, at all events in size ; but for ornament it 

 is a very good instance of the shells of the Inferior Oolite returning again with 

 modifications to their old quarters — when conditions again became suitable (cf. 

 Hudleston, ' Gasteropoda of the Inferior Oolite,' pis. xviii, xix). 



Family Naticid^;. 

 Genus NATICA, Scopoli (Adanson). 



More or less globose, smooth, rarely spirally striated, umbilicated or not, outer 

 lip sharp, inner lip thickened by a callus. 

 The records of Natica are : 



*JV. insignis (34, 43). *N. punctura (6, 9, 15, 25, 28, 43, 48, 67). 

 N. texata (65). 

 To these must be added the records of Neritopsis : 



Ner. archiaci (34, 43). *Ner. canaliculata (25, 34, 48). 



*Ner. laevigata (28). 



The record of N. insignis rests only on the statement by Lycett (' Suppl. G. 0. 



Moll.,' p. 98), " it has occurred rarely in the Cornbrash at Scarborough." His type 



is from the Great Oolite, and measures only 5"5 mm. in length, and there are no 



ornaments. It is not, therefore, to be wondered at that no specimens from the 



