1897.] NATURAL SCIENCES OF PHILADELPHIA. 407 



Europe, and prefers not to attempt its division between the upper 

 Jurassic and the lower Cretacic until a great deal more work has 

 been accomplished. Bogoslovsky terminates the upper Volgian at 

 the horizon Olcostephanus nodiger which he considers the upper- 

 most limit of Jurassic as that of Hoplites Rjasanensis is of the 

 Neocomian and the bed Olc. polyptychic and Olc. hoplitoides the 

 principal lower bed of the Neocomian. 



Pavlov, while accepting the succession of the others, classes the 

 entire Volgian group with the Jurassic, adding also a part of the 

 Neocomian of western Europe. 



With this preliminary glance at the formations in the vicinity 

 of Moscow, we were prepared to enter upon the first of the great 

 excursions, or that to the Ourals. The start was S. E. down the 

 Moskwa on the Moscow-Riazan Railway, which runs over the lower 

 arenaceous member of the boulder clay or the eluvion which was 

 laid down upon it after the erosion of the morainic upper part. To 

 Bykowa the cuts and pits show white stratified sands belonging to 

 the upper Volgian. S. E. of Lioubertzy the surface of the hills is 

 said to be formed of sands and sandstones, partially modified to 

 quartzite containing ammonites typical of the zone of Olcostephanus 

 nodiger and Oxynoticeras subclypeiforme. The lower Volgian is 

 found at Miatchkowo resting on gray and black stratified clays 

 with intercalations of dark brown argillaceous, combustible schists, 

 28 to 33 ft. in thickness, corresponding in general to the Oxfordian 

 and Sequanian. M. Nikitin was led to conclude from a study of 

 this series that at least in central Russia there exists an intimate 

 connection between the beds of Cardioceras cordatum and those of 

 C. alternans, which appears not only in the continuation of the 

 greater part of the conchifers and gasteropods from one horizon to 

 the other, but also in the gradual change and passage of some forms 

 of ammonites and other species [L. G., II.]. This conclusion is of 

 the greatest importance to the student of the Jurassic in Central 

 Russia. 



Pursuing the route through the government of Riazan along the 

 river Pronia, the lower Volgian and upper Jurassic representatives 

 are seen to disappear so that the horizon Hoplites Rjasanensis rests 

 successively, first on the Oxfordian and later, near the town of 

 Skopine, on the Callovian. The Carbonic limestones also show 

 gradually descending outcrops from the lower stages of the Mus- 

 covian, through the different levels of the lower limestones of 



