206 University of Texas Bulletin 



keel on both sides of the ventral portion. Between the rows of nodules we 

 observe on the ventral portion a rather broad, flat and smooth zone. 



With respect to the involution we observe that the last whorl seems to 

 show a tendency to form a wider curve than the preceding whorl. 



No part of our specimen shows a trace of the suture. 



According to its form and ornamentation our specimen belongs certainly 

 to Metoecoceras, and I unite it provisionally with this genus although the 

 suture is unknown. 



The species differs from M. Whitei Hyatt typus in its' flexuous ribs, but 

 it resembles the specimens figured by Stanton 1 in figures 1-2 of plates 38 and 

 called Buchiceras Swallovi. Hyatt unites it with his Metoecoceras Whitei, 

 notwithstanding that it differs much from the type. It seems that our spec- 

 imen has a smaller number of ribs than that figured by Stanton and that the 

 ribs are more flexuous. 



Our species resembles much more Pulchellia Gesliniana Petrascheck 2 than 

 the above described species. This similarity is really very great but our 

 species is distinguished by a smaller number of ribs which are also less 

 flexuous. I do not doubt that both species belong to the same group. Meto- 

 ecoceras Geslinianum Petrascheck occurs in the upper Cenomanian in 

 Saxony. 



Number of specimens : 1. 



Age : Upper Cenomanian ( ?) or lower Turonian. 



MAMMITES Laube et Bruder, Emend. Petrascheck 



MAMMITES MOHOVANENSIS sp. nov. 



PI. 12, figs. 6, 8 



In Horizon II of Cerro del Macho there has been found a well preserved 

 specimen of Mammites, and also several fragments belonging to the same 

 species. They show the following features : 



Shell globose, rather involute, with whorls of a trapezoidal or nearly 

 subquadrangular cross section, much broader than high. The umbilicus is 

 rounded. On the umbilical border we observe six thick nodules, which are 

 rather pointed and a little rounded. In these nodules begin broad, rounded, 

 radial ribs, partly simple, partly in pairs. Between these ribs are interca- 

 lated generally two secondary ribs also low and rounded, which begin above 

 the umbilical border, but without showing nodules at their beginning. On 

 these secondary, as well as on the main, ribs we find two strong and rounded 



1 Stanton, Colorado Form. 



2 Petrascheck, Amm. d. sachs. Kreideform., p. 140 (10), pi. 7 (1), figs. 3-5. 



