CRYPTAULAX. 185 



115. Cryptaulax contorta, Deslong champs, 1842. Plate XI, figs. 15 a, 15 b, 15 c. 



1842. Ceeithium contoetum, Desl. Mem. Soc. Linn. Norm., vol. vii, p. 194, 



pi. x, fig. 44. 



Bibliography, Sfc. — A fossil of the " Oolite ferrugineuse " of Les Moutiers and 

 Bayeux, where it is by no means rare. 



Description : 



Length of a fair-sized specimen . . 40 mm. 



Width . . . . 7| mm. 



Length of body-whorl to entire shell . 22 : 100. 



Spiral angle . . . .11°. 



Shell subulate, turrited, apex very sharp ; spiral angle regular. Whorls 

 numerous, pentagonal, subconcave, and separated by a broad sutural sulcus. The 

 ornaments consist of two stout spiral bands at each extremity, enclosing one or 

 two which are less prominent ; between these bands are fine spiral lines or strias. 

 There are five prominent longitudinal costae twisted from left to right, and pro- 

 ducing at the points of intersection blunt tubercles drawn out spirally. In the 

 posterior whorls the costae are for the most part in sequence, but anteriorly this 

 line becomes irregular and dislocated. 



Body-whorl relatively short, base very flat, and spirally striated. Aperture 

 suboblong, columella short ; inner lip circular, outer lip angular, especially at the 

 junction with the body-whorl, where indications of the furrow may be noticed. 

 Whorls in section ovate-oblong. 



Relations anal Distribution. — The strongly pentagonal outline of the spire, 

 besides minor differences of ornamentation, serve to distinguish Cryptaulax 

 contorta from the species last described. Both of them belong to what I may term 

 the Turritelloid section of Cryptaulax. They also more especially answer to 

 Cossmann's genus " Pseudocerithium," which is represented in the Bathonian of 

 France by Pseudocerithium densistriatum, Cossmann. Both sections of Cryptaulax 

 are unrepresented in the Great Oolite of this country. On the whole, it would 

 seem that Cryptaulax contorta and its allies might just as well be placed under the 

 Turritellidas as under the Cerithiidas. 



Cryptaulax contorta, in this country, seems confined to the Parldnsoni-zone, 

 or to the very highest beds of the Humphriesia7ius-zone, such as the Cadomensis- 

 bed at Oborne. It is especially abundant in P x at Burton Bradstock, Vitney Cross, 

 &c, and occurs on the same horizon at Stoford and at Grove, all in No. 1 district. 



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