CRYPT AUL AX. 181 



Genus — Cryptaulax, Tate, 18G9, ' Ann. and Mag. Nat. Hist.,' ser. 4, vol. iv, 

 p. 418 ; = Pseudocerithium, Cossmann (at least in part), 1884, ' L'Etage 

 Bath.,' p. 124. 



Shell elongate, pointed, with a more or less polygonal spire, ornamented with 

 longitudinal ribs, which succeed each other with a twist from left to right — a feature 

 more conspicuous in some species than in others. Suture wide, columella short, 

 aperture suborbicular to ovate, with little or no anterior canal. Peristone entire, 

 and broadly reflexed on the inner side — a shallow, oblique, posterior canal in the angle 

 formed by the body-whorl and outer lip. (Tate's diagnosis somewhat modified.) 

 Type, C. tortilis, H. and D. 



Cossmann (op. cit.) gives a somewhat similar diagnosis as regards the shell, 

 but does not mention the concealed posterior canal as one of the features of his 

 genus, Pseudocerithium, the type of which he takes to be Cerithium undulatum, 

 Quenst. 



It may be that Cryptaulax and Pseudocerithium are not exactly synonyms, 

 though M. Cossmann is now disposed to regard them as such. If we allow that 

 they are synonyms, the genus Cryptaulax certainly will cover shells which present 

 considerable differences. 



Cryptaulax occurs most abundantly in the Parhinsoni-zone, and is mainly 

 confined to No. 1 District. No species, either from the Lincolnshire Limestone 

 or from Yorkshire, has hitherto come under my notice. 



111. Cryptaulax scobina, Deslongchamps, 1842. Plate XI, fig. 10. 



1842. Cerithium scobina, Desl. Mem. Soc. Linn. Norm., vol. vii, p. 196, pi. x, 



fig. 49. 

 1867. — vabicosttm, Desl. Moore, Middle and Upper Lias, p. 83, pi. iv, 



fig. 15. 

 1869. Cryptattlax scobina, Desl. Tate, Ann. Mag. N. II., ser. 4, vol. iv, p. 418. 



Bibliography, 8fc. — Originally described from a single specimen in the Upper 

 Lias of Fontaine-Btoupefour. Moore obtained four examples from the highest 

 horizon of the Ilminster Upper Lias ; these he referred inadvertently to Cerithium 

 varicosum, Desl. Tate pointed out the mistake. 

 Description : 



Length . . . . .17 mm. 



Width . . . . .5 mm . 



Spiral angle .... 18 c 



)0 



