154 University of Texas Bulletin 



different because the ventral portion of this latter species is much more 

 flattened. This cannot be explained by different age, because the inner 

 whorls of V. irregulare n. sp. show a decidedly rounded external part. 

 The suture is also different, Vidrioceras Uddeni showing no trifid 

 lobes at all, even in a specimen larger than any one of the present 

 species; but the general arrangement of the external part of the 

 septa is very similar, although the details are different. It seems that 

 the inner whorls of our species have a suture identical to that of V . 

 Uddeni, which would make it probable that our species belongs to the 

 same genus. 



No other species seem to be known which could be compared with 

 ours. 



Age: 



V. irregulare n. sp. has been found only in the Wolfcamp division, 

 of the lowest Permo-Carboniferous. 



Number of specimens examined: 

 Two; the only ones found, so far. 



Locality: 



Immediately northwest of Wolf Camp, Glass Mountains. 



