^26 University of Texas Bulletin 



Pig. 54, venter; fig. 55, front; fig. 56, side view; natural size. 

 Fig. 57, side view; fig. 58, front; fig. 59, venter, of tiie same speci- 

 men ; twice natural size. 

 Fig. 60, external and internal suture of largest specimen; natural 



size. Tlie umbilical seam coincides with the straight limit between 



black and white. 

 Fig. 61, external and internal suture of the same specimen; twice 



natural size. 

 Pig. Q2-l?> . .Vidrioceras irregulare nov. subgen. nov. sp. — Zone of Uddenites 



(Wolfcamp formation). — Wolf Camp, Glass Mountains. 

 Fig. 62, side view; fig. 63, front; fig. 64, venter; fig. 65, external 



suture; natural size. 

 Pig. 66, front ; fig. 67, external suture of the same specimen ; twice 



natural size. 

 Fig. 68, side view; fig. 69, front; fig. 70, venter;. fig. 72, external 



suture ; natural size. 

 Pig. 71, front ; fig. 73, external suture of the same specimen ; twice 



natural size. 



