Permo-Carhoniferous Ammonoids of the Glass Mountains 157 



As Waagen, Freeh, Diener and Smith have asserted, the suture 

 of the Texan species resembles much more that of Hyattoceras; but 

 notwithstanding a general similarity, there are fundamental dif- 

 ferences. The median saddle of the siphonal lobe in Hyattoceras is 

 much lower and much less scalloped than that of the Texan forms. 

 The external saddle is a little narrower and not much higher than the 

 rest of the saddles. The lobes of Hyattoceras are more or less digitate, 

 while in the Texan species they end in a prominent point. In general 

 the saddles of Hyattoceras are more narrowly and deeply cut than 

 those of the Texan forms, and have a less triangular form, which is 

 very characteristic for all the species from the Texan Permo-Carboni- 

 ferous. This is because all the secondary lobes are cut deeply into 

 the base of the saddles of the Sicilian genus, while they are always 

 very shallow in the lower part of the saddles in the Texan species. 



In the foregoing part we have only referred to Waagenoceras HUH 

 and Waagenoceras Cnmminsi, but in the Glass Mountains occur two 

 more species which belong to the same genus and which differ very 

 little from W. HUH. These permitted of a much better study of the 

 suture than has been possible in the species described until now, and 

 they show especially that the internal suture is generically different 

 from that of Waagenoceras. The internal sutures of Hyattocera.'i 

 are not known. 



After having made clear the differences between the Texan species 

 and those forms which belong to Waagenoceras and Hyattoceras, we 

 are justified in uniting the American forms already described with 

 those which were found in the Glass Mountains in a new genus, Per- 

 rimtes, named after James Perrin Smith, to whom we owe the great 

 progress made in the knowledge of Triassic and Anthracolitic ceph- 

 alopods of America. This new genus has the following character : 



Shell discoidal, compressed on the flanks, rounded on the venter, and 

 involute. Cross-section generally parabolical and higher than broad, 

 or only a httle broader than high. Umbilicus deep and narrow with a 

 steep wall and rounded shoulder. The smaller whorls always show 

 on the mould rather deep constrictions, radial or slightly flexuous 

 on the flanks and curved on the venter with the convexity toward the 

 back. These show also on the shell, but there they are very narrow. 

 The ornamentation consists of fine lines of growth, slightly flexuous 



