^^ GEOLOGICAL MEMOIRS. 



There is still some uncertainty about tlie right arrangement of 

 several rock formations. A very considerable number of species are 

 enumerated by Phillips as common both to the Devonian and Car- 

 boniferous^ formations, being quoted from the one in his ' Geology 

 of Yorkshire/ from the other in his ' Palgeozoic Fossils.' The St. 

 Cassian beds are placed, according to the former state of our know- 

 ledge, under the head k, and in II. or the Trias period, on the 

 bomidary of I. or the Carboniferous ; whereas according to the most 

 recent geological investigations they come above the Muschelkalk or 

 k ; and the only midecided question is, whether they should be con- 

 jomed to this as its higher division with a peculiar aspect (Fades) 

 — as a coral-reef variety— or must be regarded as the oldest mem- 

 ber of the Lias formation, since they contain two or three lias ammo- 

 nites, whereas the other petrefactions rather favour the Muschelkalk. 

 The red ammonite-marbles are joined to the has, although now they 

 appear, at least in part, rather to fall under the oolite series n ; 

 whilst the ammonite-marbles with Terebratula diphya are included 

 as Neocomien under q ; it being still undecided whether the Tere- 

 bratula diphya may not be divided into two species of distinct age. 

 —In regard to the Oolite, in very many cases, it was not possible, 

 from the existing data, to determine with sufficient certainty the 

 member of the formation in which this or that organic remain oc- 

 curred ; and hence almost the entire oohte series, from the lias to 

 the Kimmeridge clay, had to be comprised tSnder one head marked 

 Ti, although in many cases where it was possible, the subdivisions of 

 this formation are more particularly distinguished in the Enumerator 

 (as n\ n% &c.).— Some Enghsh fossils, which are included under 

 the Greensand [Gault] r, should perhaps be added to the Neocomien, 

 as in England geologists have only recently begun to distinguish these 

 two^ formations. On the other hand, it is probable that some Glau- 

 conie beds f, with their organic remains, especially from Germany, 

 have been conjoined with the Greensand (Gault), the two formations 

 having hitherto been often confused ; the latter also probably con- 

 tains a number of species common to it with the Chalk f, which in 

 reality do not occur in both. Some time ago it became customary 

 to distinguish from the other deposits a peculiar nummuUte formation, 

 which had immediately to be again divided into two or three forma- 

 tions of distinct ages, of which two are placed between the white 

 Chalk and the Calcaire grossier (Grobkalk), so that the one shall be- 

 long to the cretaceous, the other to the tertiary period. Besides, 

 there is in the Etang de Berre another nummulite formation with 

 hippurites, which consequently should be classed in the lower part 

 of the white chalk. Our enumeration was produced whilst these 

 views were in process of formation, and the result of this has been, 

 that whilst the Glarus slates, which are conjoined with one nummu- 

 lite ^ deposit, are placed under r (probably however too low ?), the 

 tertiary nummulite rocks in the Paris Calcaire grossier, and at JMonte 

 Bolca, as well as in the Val Ronca, remain united with the Calcaire 

 grossier formation under t (and r), whilst only a few small nummuhte 

 deposits, whose age was not certainly determined at that time, are 



