NO. a.] DESCRIPTION OF THE FOSSILS. 75 



In spite of the resemblance in the formation of the sculpturing, and in 

 the double curve of the ribs in our form and in young forms of the Macro- 

 cephalites macrocephalus Schloth. sp., the piece before us cannot be referred 

 to this species itself, nor to the species nearly allied to it (Herveyi Sow. sp. 

 tumidum Rein. sp. Pila Nik.). In the young form of all these species, the 

 ribs are considerably finer and closer, and furthermore the whorls of a 

 corresponding size in these species are broader and lower. The lobe-line, 

 moreover, in the above-named species, has a more slender external saddle, 

 which does not exceed the first lateral saddle in size as much as in the 

 present form from Cape Flora. 



The figured fragment of Macrocephalites sp. was found loose without any 

 adhering rock on July 12th, 1896, near the margin of the glacier, 



north-west of Elmwood. It is a cast of pyrite turned into brown ironstone, 

 with an almost perfect nacreous shell. 



CADOCERAS, Fischer. 



In the ammonites before us, the genus Cadoceras is the one most 

 abundantly represented, both as regards the number of species, and the 

 number of specimens. There are, with few exceptions, only specimens of in- 

 considerable size, and these are generally greatly deformed by compression, 

 especially of the body chambers. Frequently nothing but impressions of the 

 different species remain. 



Juvenile forms of Cadoceras have hitherto been somewhat neglected in 

 ammonite literature. For the determination of young forms such as these we 

 are limited almost entirely to the works by Nikitin on Russian Cephalo- 

 poda. This author, however, gives comparatively little attention to the 

 development of the juvenile forms, of the sculpturing and the lobe-lines. 

 From Nikitin's descriptions, and from the diagrams given in the description 

 of the Cephalopoda of Elatma, it would appear that the young stages of 

 nearly all Russian Cadocerates are almost identical. 



The descriptions of young forms from the Jura of Central and Western 

 Europe are still more imperfect than the descriptions of those of Russian Cado- 

 ceras. As far as I know, no young stages of Cadoceras species from strata 

 of Central and Western Europe have hitherto been described, with the excep- 

 tion of the very imperfect accounts in Sowerby's Amm. sublosvis. In one of 



