84 University of Texas Bulletin 



seam and at the umbilical shoulder they turn suddenly forward so as to 

 form a curve, the convexity of which is directed toward the front. The 

 body chamber is unknown. 



In none of our specimens is the shell well enough preserved to show 

 the ornamentation entirely, but the moulds prove that the principal 

 ornamentation is composed of broad and flat, very low, radial ribs 

 (pi. IT, fig. 13 ). These at the umbilicus are narrow, but widen consid- 

 erably on the ventral portion, where they are separated by narrow and 

 shallow interstices. The same kind of ornamentation shows also in 

 the interior part of a whorl but there we observe also traces of very 

 fine, spirally revolving lines. The umbilical shoulder seems to have 

 possessed a number of very faint nodules or tubercles. 



The septa are well separated from each other. The suture (pi. II, 

 fig. 24-27) is nearly straight on the external part of the whorl and 

 very simple. It consists of a siphonal lobe, divided in two branches by 

 a moderately high median saddle, and of two saddles and two lateral 

 lobes. The branches of the siphonal lobe are lanceolate; the first 

 lateral lobe is funnel-shaped, symmetrical and ends in one single point ; 

 the second lobe is very wide and shallow. It lies a little below the um- 

 bilical border on the umbilical wall, and also ends in a point. The 

 median sadde of the siphonal lobe is about half as high as the external 

 saddle ; it is broad at the base and narrow at the upper end, where it 

 is notched by an indentation. The external saddle is tongue-shaped, 

 high, entire, and nearly symmetrical. The first lateral saddle is much 

 iDroader but lower than the preceding one. The internal lobes could 

 not be ascertained. 



The suture is the common one of Gastrioceras or Glyphioceras. 



Dimensions: I II III IV 



Diameter 21.0 mm (1) 16.8 mm (1) 11.4 mm (1) 8.2 mm (1) 



Width n5.2 0.72 12.2 0.73 10.8 0.95 7.6 0.93 



Height of last whorl 7.7 0.37 6.3 0.38 4.5 0.39 3.5 0.43 

 Diameter of umbili- 

 cus, between the um- 

 bilical shoulders.. ? .... 6.5 0.39 4.5 0.39 3.4 0.41 



