106 GENESIS OF THE AEIETID^. 



lowest beds and in the Bucklandi zone, but is deficient above. Asteroceras is 

 probably more fully represented than is shown in the table, since the extremes 

 of the series have been found, and, the fauna being near to that of the Cote 

 d'Or, there are grounds for anticipating the discovery of intermediate forms. 

 Agassiceras is complete in its lower forms, but Sclpionis has not yet been found. 

 The oxynoticeran series is not only quite complete, but has also a middle lias 

 representative. As regards Schlotheimia, Caloceras, Vermiceras, Arnioceras, and 

 Asteroceras, this fauna impresses one as containing the most highly modified 

 derivatives, and as being possibly a residual fauna representing an acme of choro- 

 logical migration and varietal modification so far as these genera are concerned. 

 Possibly Oxynoticeras will also have to be included in this category, and then the 

 parallel with the English fauna north of what we have called the zone of 

 the autochthones would be complete. 



Fauna of England. — Table IV. 



In this table the same regularity of succession is found in the schlotheimian 

 series as in the Cote d'Or and Rhone basins. Caloceras is again deficient in the 

 Bucklandi zone, as in the Rhone basin, but is quite fully represented and has an 

 extraordinary new form in the Raricostatus bed, Cal. aplanatum. There is also a 

 curious parallelism with the Rhone fauna in the arnioceran series, which, as in 

 that basin, has the extraordinary form of ^4.?-??. MacdonelU of the Raricostatus bed. 

 Besides the general absence of radical species, except of course the generally 

 distributed psiloceran and caloceran radicals, there is in this fauna a very impor- 

 tant fact to be noted, similar to that observed in the fauna of the Rhone. The 

 extreme modifications in the highest formations are very generally present, — 

 more so than in any other fauna. Thus, besides Cal. aplanatum and Am. .Mac- 

 donelU there are doubtful forms of Cor. Usulcatum in the Oxynotus zone. Ast. 

 Collenoti, Ast. denotatum, and the extraordinary series of var. Sagittarius of Ast. 

 obtusum, are also present. The Oxynotum subseries is complete, and the second 

 or Guibalianus subseries alone is imperfectly represented. 



The English fauna is therefore a residual fauna, not only because of the 

 absence of radicals, but because it presents a chronological and biological acme in 

 the evolution of the most highly modified and most recent forms of the different 

 series, thus clearly indicating chronologically and biologically its more recent 

 derivation by chorological migration from the older, though apparently contem- 

 poraneous, faunas of the autochthonous zone. 



Fauna of tiie Province of Central Europe. — Table V. 



This table has already been amply explained, with the exception of certain 

 general facts. The independent origin of the schlotheimian and psiloceran series 

 is in strong contrast with the Northeastern Alps fauna, which as tabulated in 

 Table VI. shows that Psiloceras and Schlotheimia are connected by means of 

 intermediate wrehneroceran forms. Schlotheimia and Caloceras are character- 



