424 Revieivs — MM. A. Pavloio and G. W. Lamphigh — 



These may be taken in descending order, attention being directed 

 cliiefly to the lower Volga region, of which the series of beds is the 

 most complete. Below the Gault in this region there are clays 

 containing concretions of marly limestone, and characterized by 

 Jloplites Deshayesi, Amalfheus biciirvatus, and by large forms of 

 Ancyloceras, which are found both in concretions and in the clay 

 itself. The presence of Gault cephalopods clearly indicates the 

 horizon to which these clays belong. The Gault clays rest upon a 

 thick series of more or less marly and gypsiferous clays, of which 

 the upper part is poor in fossils, making it difficult to establish the 

 lower boundaries of the Gault. But a little lower down two 

 horizons are apparent, characterized by different Ammonites ; the 

 upper one with Olcostephanus {Simbirshites) Decheni, S. discofalcatus, 

 S. progrediens, S. iimhonatns, S. speetonensis (fasciato-falcatus, Lah.), 

 S. Barboti, Belemnites Jasikowi, B. brunsvicensis, B. absolutiformis, 

 the lower, which is thinner, containing Simbirskites versicolor, S. 

 inversus, Belemnites Jasikowi, B. absolutiformis. Comparing this 

 part of the Simbirsk section with that of Speeton (see Table) the 

 striking resemblance between the two faunas is apparent, as also the 

 similarity in the order of their succession. The number of forms 

 common to both leaves no room to doubt that in the Simbirsk 

 horizon we have the exact representative of the zones of Olcostephanus 

 (Simbirskites) speetonensis, and S. subinversus of Speeton. There 

 are, it is true, some dissimilarites between the beds of the two 

 countries, but these are unimportant, and fresh researches might 

 completely negative them. The zone of S. Decheni and S. discofal- 

 catus is developed also in the neighbourhood of Moscow (Gres de 

 Worobiewo) and contains Crioceras Matheroni. On descending 

 lower in the series, however, the striking resemblance between the 

 Russian and Speeton beds is no longer discernible. For, while at 

 Speeton the succeeding zone (c. 8 to c. 11) is characterized by 

 Moplites regalis, Holcodiscus rotula, Astieria Astieri, Hoplites Bou- 

 baudi, Belemnites jacidum (representing the upper part of the 

 " Claxby Ironstone " of Lincolnshire), this zone is entirely wanting 

 in the Simbirsk' region. Its absence is the more remarkable since 

 the following zone, which forms the base of the Hoplites regalis beds 

 of Speeton, is common to both countries, although in Russia it is 

 only developed in certain places. The zone in question (D. 1 to 

 D. 3) is met with in the neighbourhood of Syzran (village of 

 Kachpour), and its stratigraphical position is found to be above that 

 of the upper zone of the first stage of Eouillier ( = Volgien superieur). 

 It here contains Olcostep)hanas (Bolyptyrhites) Keyserlingi, P. ramu- 

 licosta, P. gravesiformis, Belemnites lateralis, B. subquadratus, and 

 many other forms. No trace of this interesting fauna has been met 

 with in the environs of Moscow. Remains of plants in arenaceous 

 beds, of Wealden or Purbeck age, are found here, and these beds 

 rest upon the upper stage of Rouillier, which near Syzran forms the 



' Simbirsk is a province situated in the western part of East Eussia, nearly due 

 •west of Moscow. 



