THE LIAS AMMONITES. 



Fig. 161. — Stephancceras annulatum Sow. 



Ag. 162. — Stephanoceras commune, Sow. 



Stephanoceras Brackenridgii, Sow. 

 ■ — - Brocchi, Sow. 



— Brongniarti, Sow. 



— coronatum, Brug. 



— Blagdeni, Sow. 



Stephanoceras Deslongchampsii, cCOrh. 



— Gervillii, Sow. 



— Humphriesianum, Sow. 



— Sauzei, (T Orb. 



— linguiferunij d'Orb. 



The group which Stephanoceras niacrocepJialum, 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 Cornbrash 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 KeUoway, 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 Macrocepliali 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 found 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 

 1 'Jurassic Cephalopoda;' " Paleeontologia Indica," p. 108, 1873. 



