A New Ammonite Fauna of the Lower Turanian of Mexico 205 



deep furrows as in Hyatt's plate 13, figure 3, but simply an undulation. As 

 far as the suture is visible it corresponds with that of M. Whitei, especially 

 with that of plate 14, figure 8 of Hyatt. I do not identify my specimens 

 with M. Whitei because they are not sufficiently well preserved, but I am 

 sure that they belong to the group of M. Whitei. 



We know very little about the stratigraphic position of M. Whitei; some 

 of Hyatt's originals have been found in the Kanab Valley, Utah. According 

 to Walcott and Stanton 1 the species occurs there up to a height of 335 feet 

 above the base of the Cretaceous. Stanton refers that division to his Colo- 

 rado Formation which probably contains several horizons, perhaps from 

 the upper Cenomanian, or at least from the lower Turonian to the Emsche- 

 rian. For the determination of the age of our beds the species found in the 

 United States do not help us much. On the other hand, we do not know any 

 European form which might be identified with our species, although this 

 has a great similarity with Pulchellia Gesliana Petrascheck from the upper 

 Cenomanian of Saxony, as we have shown in the stratigraphical part. 



Number of specimens : 2. 



A//e: Upper Cenomanian (?), lower beds of Cerro del Macho. 



METOECOCERAS sp. nov. 

 PI. 12, figs. 1-3 



The collection of Dr. Haarmann contains a specimen of Metoecoceras 

 which is certainly different from the species described above ; unfortunately 

 we do not know in which horizon this specimen has been found ; according 

 to its petrographical character it belongs to Horizon I, but it might have 

 been found also in Horizon II. Its features are : 



Shell discoidal, very involute, with whorls of a lanceolate cross section 

 truncated in the ventral part, much higher than broad. The flanks are a 

 little convex, the ventral' portion is flattened. The ornamentation consists 

 of rather strong ribs, which are slightly flexuous and which bend forward. 

 These begin near the umbilical border, where they are slightly thickened, 

 but do not form nodules. Part of these ribs bifurcate below the middle of 

 the height of the flank. Between these main ribs we find other secondary 

 ones intercalated which begin in different heights of the flank, and which at 

 their beginning are less strong than the main ribs. All the ribs show near 

 the ventral shoulder a slight thickening of a kind of very low and rounded 

 nodules ; on the ventral shoulder the ribs end in a nodule which is longi- 

 tudanally elongated. These nodules form together a kind of interrupted 



'Stanton, Colorado Form., p. 35. 



