74 POMPECKJ. JURASSIC FAUNA OF CAPE FLORA, [norw. POL EXP. 



umbilicus, the ribs describe a short umbonal curve ; up to half the height of 

 the whorls, they lean a little. Hence the ribs describe a flat curve, concave 

 towards the front. Across the outside they run straight, or are almost im- 

 perceptibly bent forward. Long and short secondary ribs are interpolated from 

 the outside. At about half the height of the whorls they meet the primary 

 ribs, or they stop short near the primary ribs. Through the interposition of 

 the secondary ribs, most of the primary appear to be bifurcate. Where 

 the secondary ribs commence, the primary are particularly strong, and 

 on well-preserved shells almost sharp-edged. 



The adjacent lobe-line is a perfect representation 



fi of a greatly simplified lobe-line of Macrocephalites 



y^iM Kcettlitsi n. sp. (cf. p. 71 letterpress fig. 12.) The 



Fig 13. Macrocephalites ^^'^^ lateral saddle, and both the succeeding small 



sp. Lobe-line of PL II, saddles, are bipartite, and the lobes tripartite. 

 fig. 11. 2 X enlarged. 



Remarks. Judging from the lobe-line, the piece 



figured very probably belongs to a young form of Macrocephalites KcettUtzi 



n. sp., or to the varieties of Macrocephalites Ishmae Keys. sp. described by 



Newton from Windy Gully. As the early stages both of this form, and of 



Macrocephalites Ishmae Keys. sp. are not known, the piece before us cannot 



be specifically determined. 



Apart from the resemblance of its lobe-line to that of Macrocephalites 

 KcettUtzi, it is clear that the figured piece is a Macrocephalites, from the 

 character of the sculpturing on the doubly curved primary ribs. 



The same general character is to be observed in the sculpturing in young 

 forms of Macrocephalites macrocephalus Schloth. sp., Herveyi Sow. sp., 

 tumidnm Rein sp. etc. from the Callovien of Suabia and Franconia, and 

 moreover, in the young specimen of a Macrocephalites pita. Nik. from 

 Czenstochau in Poland^, of which Bukowski gives an illustration. The 

 same character is also to be seen in the sculpturing of the numerous young 

 specimens of Macrocephalites, which Waagen describes .from the Jura of 

 K^utch in India. It is worthy of remark in all these young forms, that the 

 young specimens of Waagen's group of "Macrocephali Rectecostati" also 

 always have curved ribs. 



■ Gejza Bukowski, 'fjber die Jurabildungen von Czenstochau in Polen. Beitrage zur 

 Palaeoutologie Oesterreich-Ungarns etc. 1887', vol V. pi. XXVI. (II) fig. 17. 



