W. E. Hudleston—On the Yorkshire Oolites. 249 



Belations and Distribution.— This form has so many relations, some 

 of which have been referred to Melania (Chemnitzia), some to 

 Cerithiim, that to go into the question of its affinities thoroughly 

 -would be a serious task. Melania (i.e. CeritMum according to 

 D'Orbigny) undulata, Desl., would seem not to be far off. 



In Yorkshire this particular variety of the vetusta group is con- 

 fined exclusively to the principal shell bed of the Dogger, where 

 it is tolerably plentiful, but seldom well-preserved. The apical 

 whorls are similar to those of Ch. vetusta. 



18. — "Chemnitzia" vetusta, var. seminuda. PI. VI. Fig. 13. 



Description. — Specimens from the Dogger (zone 1), Peak (Blue 

 Wyke). Leckenby Collection. 



Lengtli 23 mm. 



Wicfih 4-5 „ 



Spiral angle IS'^'o. 



Shell conical, elongate. Spire composed of about 11 whorls, 

 which are nearly flat, of moderate height, and rather close together. 

 They increase with great regularity so as to render the general 

 outline extremely conical. The subapical whorls (those at the very 

 top are effaced) are ornamented with numerous delicate longitudinal 

 ribs, very slightly curved. Lower down this ornament becomes 

 very faint, and expires in the body-whorl, or is merely represented 

 by obscure sinuous lines. 



The base is small, rounded and quite smooth. The anterior margin 

 of the aperture is broken away. Apparent shape elliptical, with a 

 thin outer lip. 



Belations and Distribution. — This rather marked form also belongs 

 to the vetusta-gvoup, from the other species of which it is clearly 

 separated by the smoothness of the later whorls. Eare. Two speci- 

 mens from the Dogger in the Leckenby Collection, and one in my 

 Collection. 



19. — " Chemnitzia " VETUSTA, var. ? scalariformis. pi. VI. Fig. 14. 



1842. Melania scalariformis, Desh., Deslongchamps, Mem. Soc. Linn. Norm. vol. 



vii. p. 218, pi. vi. figs. 63-66. 

 1847. CeritMum subscalariforme, D'Orb., Prod. vol. i. p. 271. 

 1850. Chemnitzia ?vettista, Phil., Morris and Lycett, Great Ool. Moll. p. 114, 



pi. XV. fig. 7. 



Description (Fig. 14). — Specimen fi'om the Millepore Bed (zone 2), 

 Cloughton Wyke (Sycarham). Leckenby Collection. 



Length 15 mm. 



Width 4-5 „ 



Spiral angle 19°. 



Shell conical, subturrited, elongate. Whorls about 10 ; short, very 

 slightly convex to flat; suture well marked. Longitudinal {i.e. 

 transverse) ribbing strong, and sloping to the left, with a slight 

 curve, wide apart. These ribs are decussated towards the posterior 

 margin of the lower whorls by a line of nodes, which gives a 

 crenulated appearance to this shell. 



Base strongly ribbed spirally. Aperture elliptical, with a probable 

 notch on the anterior extremity of the inner lip. 



