A New Ammonite Fauna of the Lower Turanian of Mexico 219 



seems to be entirely smooth, no nodules can be observed on the umbilical 

 border. The suture is similar to that of the group of Vascoceras Kossmati 

 but it is not complete enough for a drawing. 



Dimensions : 



Diameter 106 mm. (1) 



Height of the last whorl 43 mm. 0.41 



Width of the last whorl 72 mm. 0.68 



Diameter of the umbilicus 22 mm. 0.21 



One of the specimens is a little obliquely deformed which makes the de- 

 termination still more difficult. The species resembles externally much 

 Ammonites arnesensis Choffat 1 , the generic position of which is equally 

 doubtful; it seems to me to belong to Vascoceras or to a new subgenous, 

 the suture being quite different from that of the type of the genus. 



In one of our specimens the suture is not visible ; in the other one we see 

 parts of it which are similar to the elements of the suture of Vascoceras 

 Angermanni. Therefore I place our species provisionally in the genus 

 Vascoceras. Externally this species resembles somewhat Vascoceras Ar- 

 germanm but the umbilicus is wider, the general form less globose, and 

 the whorls are less broad in relation to their height. 



Number of specimens: 2. 



Age: Lower Turonian (Salmurian), upper horizon. 



VASCOCERAS MOHOVANENSE sp. nov. 

 PI. 18, figs. 1-2 



Dr. Haarmann collected in the upper bed of our Salmurian a juvenile 

 individual of a cephalopod which certainly represents a new species. Its 

 features are : 



Shell small, subglobose, quite involute with whorls of trapezoidal cross 

 section, much broader than high. The flanks are somewhat flattened, 

 as is also the ventral part. This gives the cross-section its angular form. 

 The umbilicus is narrow and deep, the umbilical wall is abrupt, the um- 

 bilical border is angular. The ornamentation consists in the last whorl of 

 about eleven high and pointed nodules (nearly all broken in the present 

 specimen) on the umbilical border; from each of these generally starts a 

 pair of ribs. Between this pair of ribs now and then secondary ribs are 

 intercalated which begin above the umbilical border. The ribs are thick 



'Choffat, Especes nouv. ou peu conn., p. 68, pi. 13, fig. 10 ; pi. 14, fig. 3, pi. 22, fig. 39. 



