252 
THE LIAS AMMONITES. 
Stephanoceras Brackenridgii, Sow. 
— Brocchi, Sotv. 
— Brongniarti, Sow. 
— coronatum, Bnig. 
— Blagdeni, Sow. 
Stephanoceras Deslongchampsii, d'Orb. 
■ — Gervillii, Sow. 
— Humphriesianum, Sow. 
— Sauzei, d'Orb. 
— linguiferum, d'Orb. 
The group which Stephanoceras macrocephalum, Schloth., represents, appears to stand 
apart from the preceding forms, for all these shells are characterised by their globose 
figure, arising from the extreme involution of the shell, by the narrowness of the umbilicus, 
with its steeply-inclined walls, and remarkable lobe-line. The siphonal lobe is extremely 
long, and much broader, but not longer nor extending more downward than the principal 
lateral ; the second lateral is smaller and reaches to the umbilical border. Such is the con- 
dition of the lobes in Stephan. modiolare, Llwyd. This group has very few species in the 
European rocks. They all occupy a very limited horizon, commencing with Stephan. 
macrocephalum in the Corn brash of England, and from the same horizon in Germany. 
They are found likewise in the Kelloway Rock, and in the dark clay bed which lies above 
the Kelloway, and belongs to it, at the base of the Oxford clay. 
The Indian species are numerous and well preserved, twenty-three species having been 
figured and described from the Kachh Jura of Cutch, by Dr. W. Waagen.^ " Of these 
species those identical with European forms occupy also in Kachh, as in Europe, the true 
' Macrocephalus-beds.' The other species, however, range from the uppermost beds of 
the Pachum-group up to the Kuntkote sandstone, i.e. from the highest beds of the Bath- 
to the uppermost beds of the Oxford-group, each of them keeping in the meantime strictly 
to its own layer. 
" Long since it was apparent that the group of the Macrocephali was one of the most 
important among all the Jurassic Ammonites, not only because they characterised a well- 
defined horizon in the European Jurassic series, but also because very nearly allied forms 
had been foimd over the whole world ; and it was to a certain degree supposed that these 
also ought to signify about the same geological time, indicating for the beds in which they 
^ 'Jurassic Cephalopoda;' " Palseontologia Indica," p. ICS, 1875. 
