190 



horseshoe-shaped or elliptical in cross-section. The penultimate 

 whorl is embraced by a little more than half the height of the 

 last whorl. The umbihcns is deep and narrow so that little 

 more than the inner margin of the first whorls is visible. In 

 the region of the body-chamber the umbilicius widens some- 

 what more rapidly and forms a more open spiral than before. 

 The length of the body-chamber and the shape of the shell- 

 aperture are not known. 



The whorls are covered with strong ribs, which traverse 

 their sides in slight curves, having their convex side back- 

 wards. At a distance of somewhat less than half the height of 

 the whorl, these ribs divide into two or three branches or, 

 more rarely, shorter ribs coming from the external margin are 

 interposed between the longer primary ribs. The ribs cross the 

 external margin in gentle curves, which have their convex side 

 forwards. Upon the last whorl or body-chamber the ribs become 

 gradually broader, less prominent and further apart than they 

 are on the preceding whorls. In some specimens, the sculpture 

 of the last whorl has almost disappeared. 



The suture-lines cannot be traced with certainty; they appear 

 indistinctly in a few places on the surface of the weathered 

 casts. It can, however, be observed that the lobes and saddles 

 were strongly and deeply divided. 



The Greenland specimens differ from Macrocephalites Ishmce, 

 Keys, typ.'^) and from var. arctic a, Newton^) by Iheir more flat- 



') Keyserling, A. und Krusenstern, P. 1846. Wissenschaftliche Beob- 

 achtungen auf einer Reise in das Petschora-Land im Jahre 1843. 

 St. Petersburg, p. 331, tab. XX, flg. 8- 10, tab. XII, fig. 15. 



PoMPECKJ, J. F. 1899. The Jurassic Fauna of Cape Flora, Franz 

 Josef Land. The Norwegian North Polar Expedition 1893—1896. Scien- 

 tific results edited by Fridtjof Nansen. П. London &c. p. 72. 



2) Newton, E. T., and Teall, J. J. H. 1897. Notes on a collection of rocks 

 and fossils from Franz Josef Land, made by the Jackson Harmsworth 

 expedition during 1894 — 1896. Quart. Journ. Geol. Soc. London, vol. 53, 

 p. 500, tab. 40, fig. 1. 



