J. ^Y, Judd — On the use of the term Neocomian. 225 



made valuable contributions to the subject, and to some extent) 

 anticipated later and fuller discoveries, our attention m particularly 

 attracted by the labours of Auguste de Montinollin, of Neuehatel. 

 This able geologist was engaged, during the years 1825-7, in closely 

 studying the rocks (then supposed to belong to the Upper Oolite) in 

 the neighbourhood of his native town ; and in 1828 was able to 

 carry a considerable collection of their fossils to Paris, and to com- 

 pare them with the palasontological collections of M. A. Brongniart. 

 He was thus led to the conclusion that the Swiss fossils had close 

 affinities with those of the Lower Cretaceous, and that the beds of 

 Neuehatel were near in age to the Lower Greensand. At least as 

 early as 18^3 M. de Montmollin read before the " Societe des 

 Sciences Naturelles de Neuehatel " his celebrated " Memoire sur le 

 terrain Cretace du Jura," though it was not published until 1835, 

 while the accompanying map did not appear until 1839. Some of 

 the earlier labours of Agassiz were devoted to the study and descrip- 

 tion of the fossils of these beds, and the discussion of the relations of' 

 the strata themselves. 



In 1836 MM. Voltz and Thirria published their " Memoire sur le 

 terrain Jura-cretace de la Franche-Oomte," in which they point out 

 that the beds in question form either the lower part of the Greensand 

 formation, or else constitute a distinct formation, situated between; 

 the Jurassic and Cretaceous. 



Li consequence of the differences of opinion which existed on the 

 subject of the classification of the beds of the Jura, two special 

 conferences of geologists took place — that of Neuehatel in 1834, and 

 that of Besan9on in 1835. At the latter of these M. Jules Thurmantt 

 pointed out the strong reasons which existed for considering the 

 strata in question as constituting a new geological horizon, and 

 proposed for it the name Neocomien, from the Latin name (Neo- 

 comum) of the town about which they are so well developed, and 

 where they were first studied. This happy suggestion was at once: 

 adopted by M. de Montmollin and the other geologists present, and 

 the term Neocomien soon obtained an extensive currency in France; 

 Switzerland, and Germany. 



A year or two later the existence and characters of beds of the 

 same age on the eastern side of the Paris basin were described 

 almost simultaneously by MM. La Joye, Leymerie, Eoyer, and 

 Gornuel. 



■' In the typical district of the Jura the Neocomian series is not 

 6omplete in its upper part. For the higher beds, not represented 

 in that district, D'Orbigny proposed the name Aptien ; and later he 

 separated the upper part of the Neocomian of the Jura, under the 

 name JJrgonien. D'Archiac, however, has well shown, in the fourth 

 and fifth volumes of his " Histoire des Progres de la Geologie," that 

 the Aptien, Urgonien, and Neocomien etages of D'Orbigny are but 

 portions of one great formation, to the whole of which the term 

 Neocomian is properly applied. It is not necessary here to pass iii 

 review all the terms — such as Ehodanien, Barremien, Valanginien. 



VOL. YII. — NO. LXX. 15 



