MARCOU ON THE NEOCOMIAN AND THE WEALDEN ROCKS. 3 
D'Orb. ; Stylina intricata, From. ; and Thamnasircea dumosa, From. 
Typical localities ; vicinity of Salins, Gray, Besan9on, Montb61iard, and 
Bori'entruy. 
The Salins Limestone terminates the Jurassic strata, and a well- 
marked discordance of stratification exists between it and the Neooo- 
mian rocks; a discordance varying from 5° to 15°, and which may be 
seen on all the flanks of the different longitudinal valleys of the Jura. 
The Neocomian rocks are divided into three groups : the Lower 
Neocomian, or St. Croix group; the Middle Neocomian, or Chateau 
group; and the Ujiper Neocomian, or Noirvaux group. 
The Lower Neocomian has its type in the vicinity of St. Croix, a 
village in the Canton de Vaud, celebrated for the numerous and suc- 
cessful researches of Dr. Campiche, who has collected there the most 
complete set of Neocomian fossils in existence. Professor Pictet de- 
scribes them in his Materiaux pour la Paleontologie Suisse, seconde serie ; 
Description des fossiles du Terrain cretace de Ste. Croix, now in course of 
publication. The St. Croix group may be divided into three princi- 
pal parts, (a) the Villars Marls, (6) the Auberson Rocks, and (c) the 
M^tabief Limonite. 
(a). The Villars Mavis {Marnes de ViUars), forty feet thick, consist 
of very hard, grey marls, alternating near the top with marly and 
very compact limestone. In some places, such as Renaud du Mont, 
La Riviere, and Foucine, the marls become green and even variegated, 
and then ' contain layers of white gypsum and dolomitic limestone. 
Professor Lory of Grenoble has found freshwater shells in this division, 
such as PZaMortt's Loryi, Coq.; Physa Wealdina, Coq.; Paludina, Cyclas, 
Anodonta, &c. ; and M. Renevier has lately discovered the Corhula 
alata. Sow., which indicates a mixture of brackish-water animals. The 
typical localities for fossils are, Villars-le-lac near Morteau, Charix 
near Nantua, Jongue, Les Rousses, and Cinquetral near St. Claude. 
(h). The Auberson Rocks {Roches dl Auberson), eighty feet thick, are 
composed of a series of compact, whitish, oolitic limestones, with beds 
of blue and yellow marls, varying in thickness from half-a-foot to ten 
or twelve feet, intercalated near the base. The marls contain in great 
quantity a small sea-urchin called Toxaster Oampichei, Pic, and a small 
Terebratula related to the Ter. hiplicata, var. acuta, von Buch. In the 
limestone beds are found, Strombus Sauiieri, Coq.; Sigaretus Fidanceti, 
B 2 
