EEMARKS. 87 



Leconte, and have collected some forms in California and other localities in the 

 United States. There are also, a few species in the collections at San Francisco, 

 but these and the fossils collected at Vancouver's Island, and described by Mr. 

 Whiteaves of the Canadian Survey, which we have also seen at Ottawa, show a 

 mixture of the species of the European province besides a number of peculiar 

 forms. Though not disposed to give any final opinion at present, the facts jus- 

 tify the suggestion that the North American assemblage of species has a distinct 

 facies of its own, and ought to be separated at least provisionally from the South 

 American and all European faunas as the province of North America. 



The collections so far made in the Jura show that there is a prevalence of 

 the Arietidas in the Lower Lias, and of the species of Perisphinctes in the Upper 

 Jura of the South American province, whereas these are less abundant in North 

 America. Whiteaves also shows a mixture of the species of the Cretaceous with 

 those of the Jura at Vancouver's Island, which, together with the peculiar 

 species found there, suggests a distinct basin for that locality as compared with 

 the Jura farther to the south and east in the United States. The fossils so far 

 found in the district of Atacamas, and at localities in the Argentine Republic, 

 show that a provisional separation should be made between this region and that 

 of northern Peru, and that two basins at least, if not more, exist in the Jura of 

 the South American province. 



Both the physical features of the distribution of the deposits and the faunas 

 appear, therefore, to make it doubtful whether the terms Mediterranean, Cen- 

 tral Europe, and Russia can be assumed as appropriate names for the homozoic 

 bands of the Jurassic period in America. It would be preferable to adopt for 

 these bands the nomenclature of Marcou. Thus, the Bande 1 Homozoique Cen- 

 trale of Marcou would become the Tropical Homozoic Band ; the Bande Homo- 

 zoique Neutrale du Nord of Marcou would become the ' Temperate Homozoic 

 Band ; and the Bande Homozoique Polaire du Nord of Marcou would become the 

 Polar Homozoic Band. These bands could then be subdivided into provinces 

 and basins according to the faunas, and the real facts of the distribution of 

 forms more clearly shown than by using the names of European regions for 

 that purpose. 



Waagen, in his article " Ueber die Zone des Amm. Sowerbyi," has traced in a 

 general way, following out simply the physical features of the distribution of the 

 Jura, the following basins : I. South German Basin, consisting of Suabia, Fran- 

 conia in Bohemia, and southeastern Baden " und des Randen." II. Helvetic 

 Basin, including Switzerland, departments of Doubs, Jura, and Ain, also Rhone, 

 Saone et Loire, Cote d'Or, Haute Saone, Haut Rhin, and Bas Rhin, and the neigh- 

 boring deposits in the south of Baden. III. Mediterranean Basin, including the 

 departments of Lozere, Aveyron, Herault, Gard, Ardeche, Drome, Basses Alpes, 

 Var, and Bouches du Rhone, and suggests an Italian basin for the Southern Alps. 

 IV. Pyrenean Basin, including the departments of Lot, Charente, Charente 

 Inferieure, and perhaps Deux Sevres. V. Parisian Basin, including the depart- 



1 The use of the word zone instead of band is likely to lead to confusion, on account of its employment 

 in geology for the synchronous faunas of the same beds, and we think it ought to be avoided. 



