N0 . 2.] DESCRIPTION OF THE FOSSILS 99 



I wish to point out that the form from the Russian Jura, which d'Orbigny 

 at first 1 determined as Amm. Ijeachi subsequently 2 as Amm. Marice is 

 allied to our Quenstedtoceras vertumnum, but differs from it in its finer 

 sculpturing, without single ribs, and in its lower saddles (provided 

 d'Orbigny's drawing is correct). Nikitin 3 refers the form in question to the 

 synonyms of Quenstedtoceras Lamberti Sow. sp. It is probable that both 

 d'Orbigny's and Nikitin's determinations are wrong, and that (his Amm. Leachi 

 d'Orb. non Sow. = Amm. Marice d'Orb. e. p. = Quenstedtoceras Lamberti 

 (Sow.) Nik. e. p., belongs to the group of Quenstedtoceras Mologce-Ryb- 

 inskianum. 



Quenstedtoceras vertumnum Sintzow and Mologce Nik. are the Quenstedto- 

 ceras in which one of the generic characters the formation of the keel- 

 line is quite suppressed, or perhaps only nearly so, i. e. with the exception 

 of the whorls of still younger stages than those hitherto studied. These 

 forms have consequently still more resemblance to the Cadocerales than all 

 other species of Quenstedtoceras, which in adult stages also become broad and 

 depressed. 



In the material collected by Professor Nansen in the neighbourhood of 

 Cape Flora, the following forms of Ammonites may be recognized after the 

 above investigations: 



Macrocephalites Kcattlitzi n. sp. 



S P- 



Cadoceras Tchefkini d'Orb. sp. 



Nanseni n. sp. 

 sp. ex. aff. Nanseni (n. sp.) 

 Frearsi (d'Orb. sp.) Nik. 

 sp. (?Elaimee Nik.) 

 sp. indet. 

 Quenstedtoceras vertumnum Sintz. 



1 Murchison, Verneuil et Koyserling, 'Geologic do la Russie" Vol. II. Paloontologie, p. 



438. PI. XXXV. fig. 7-9. 



3 'Pal<5ontologie fran^aise* Terr. jur. I, PI. 179. fig. 7-9. 

 S. Nikitin, 1881. Rybinsk etc. p. 46. 



