70 POMPECKJ. JURASSIC FAUNA OF CAPE FLORA. [NORW. POL. EXP. 



Among the material collected by Prof. Nansen, three genera of ammon- 

 ites may be pointed out Macrocephalites v. Sutner, Cadoceras Fischer, and 

 Quenstedtoceras (Hyatt) Nikitin. If Newton's designation of the above-men- 

 tioned fragment is correct, a fourth genus, Cosmoceras Waagen (sub-gen. 

 Kepplerites Neum.), is further represented in the Jura of the neighbourhood 

 of Cape Flora. 



MACROCEPHALITES, V. Sutner. 



GROUP OF MACROCEPHALITES ISHMAE Keys. Sp. 



Macrocephalites Kcettlitzi 1 n. sp. 



PI. II. fig. 12 a-e. 

 Letterpress fig. 12. 



There is only one, to some extent weathered cast preserving small frag- 

 ments of the shell. It belongs to a form with a very narrow umbilicus, 

 and almost completely encircling whorls, and exhibiting the following dimen- 

 sions: 



Diameter 60 mm. = 1. 



Width of the umbilicus 7 = 0.12. 



Height \ of the last 30 mm. = 0.50. 



Thickness / whorl 34 = 0.57. 



On the flanks, and on the external surface, the whorls are broadly con- 

 vex, while they incline steep and suddenly towards the umbilicus. At the 

 last two whorls the thickness is somewhat greater than their height. The 

 greatest thickness is at a point a little below half the height of the whorls. 

 The section of the whorls is approximately horse-shoe shaped. The inner 

 whorls encroach so largely upon the succeeding ones that the height of the 

 outer whorls, measured in the median plane, is less than half the height of 

 the entire whorl. 



The umbilicus is very narrow (12% of the diameter) and deep, with al- 

 most vertical walls. In the umbilicus nothing is to be seen of the inner 

 whorls but the steep umbilical surface. 



1 Named in honour of Dr. Reginald Kcettlitz, member of the Jackson-Harmsworth Ex- 

 pedition, merited by his most valuable researches of the geology of Franz Josef Land, 

 and especially of Cape Flora. 



