96 GENESIS OF THE ARIETIDiE. 



by very few forms in the basin of the Rhone, and Ver. spiraiissimum appeared first 

 in the Lower Bucklandi bed. 



In England the number of varieties or forms is not equal to either of the 

 three faunas above mentioned, but the transitional forms are present. Wright, in 

 his "Lias Ammonites," gives a section at Red Car, and A.mm. Conybeari is cited as 

 occurring in the lowest stratum of the Bucklandi zone. With regard to the Eng- 

 lish fauna, one can see, in spite of the large size and the multitude of speci- 

 mens, that the small number of distinct species and the entire want of autoch- 

 thonous species, or varieties, indicate a purely residual fauna composed of un- 

 modified forms. This basin is north of the zone in which autochthones arose 

 during the Lower Lias, and the basin of the Rhone lies south of this zone, and 

 both are residual faunas. Ver. Conybeari is mentioned by several authors as 

 occurring in North Germany and in Luxemburg, but, so far as we have seen, 

 other forms of this genus have not been cited, and Vermiceras appears to have 

 had but slight development in these basins 



The facts, so far as now known, are opposed to the inference that this series 

 originated in the Northeastern Alps. On the contrary, it seems more likely 

 that it began in the Caloceras bed of South Germany with a variety of Gal. 

 laqueum, and subsequently appeared as Ver. prespiratissimwn in the fauna of the 

 AiTgulatus zone in the Mediterranean province. The series, however, did not, 

 either at this time or on any subsequent horizon in this province, meet with 

 very favorable conditions for the evolution of new forms. It must be remarked, 

 also, that the variety of Conybeari figured by Hauer and by Herbich has a whorl 

 quite distinct from that which occurs most commonly in Central Europe. It is 

 more like the degenerate variety of Conybeari, which is usually called Bonnardi, 

 though apparently of smaller size. 



Arnioceras. 



There are quite a number of forms described by various authors as having 

 been found in the Mediterranean province, but they have all been found in hori- 

 zons above the Lower Bucklandi bed. This may be seen by our Table VI., 

 and also in the fact that Suess and Mojsisovics found no species of this genus in 

 the Osterhornes mountains, the beds above the Bucklandi zone being unfossil- 

 iferous, and Paul states, in his article " Die Nordliche Arva," 1 that only one 

 species of this series was found in the Lias, and this occurred in the beds above 

 the Bucklandi zone. 



My notes on the collections at Stuttgardt and Tubingen do not show so rich 

 a fauna as in the Cote d'Or, nor do Quenstedt's publications indicate so full a 

 development of the series as in that basin. Thus, though the series began in 

 the Angulatus zone, as shown in Fraas's collection, it did not reach its acme of 

 development in the South German basin. The evolution of Arnioceras in the 

 fauna of the Cote d'Or is exhibited in the Semur collection, and in Boucault's col- 

 lection of the Museum of Comparative Zoology. The large number of forms in 

 1 Jalirb. geol. Reichsans., XVIII., 1868, p. 233. 



