Permo-C arboniferous Ammonoids of the Glass Mountains 1 59 



lobes cut into it deeply in the upper half while in the lower half they 

 are extremely shallow. The first and second lobes are similar to the 

 antisiphonal. but much shorter and comparatively broader; the only 

 auxiliary lobe clearly visible is more irregular, and asymmetrical but 

 ends likewise in a sharp point. The first and second lateral saddles are 

 similar in shape to the internal, but less complicate and relatively 

 stouter ; the only auxiliary saddle visible is similar to them but much 

 simpler. Saddles and lobes decrease rapidly in height and depth from 

 the antisiphonal lobe and internal saddle toward the umbilicus. 



The foregoing diagnose shows that our genus is not very nearly 

 related to Waagenoceras. Especially characteristic are the internal 

 lobes. While in Waagenoceras'^ the antisiphonal lobe is relatively 

 short and broad, with two high adventive saddles inclined toward the 

 center of the antisiphonal region (compare pi. X, fig. 28), that lobe 

 is extremely long and narrow in Perrinites with two pairs of short 

 adventive saddles inclined toward the center of the antisiphonal re- 

 gion. While in Waagenoceras the internal saddles are curved and 

 bent over toward the center of the antisiphonal region, they are 

 straight in Perrinites. 



The diflferences between our new genus and Hyattoceras have been 

 demonstrated already above. The two genera are to a certain degree 

 related, but the differences in shape, especially with respect to the um- 

 bilicus, and the suture, are constant. 



Diener^ has described from the Productus shales of Byans, India, 

 a Hyattoceras nov. sp. ex. aff. H. Cuiiuninsi White. I doubt very 

 much that this species belongs to Hyattoceras because it does not 

 show the characteristic phylloid ends of the saddles and has only two 

 lateral and two auxiliary lobes. It certainly is generically different 

 from Perrinites, which in specimens of the same size shows already 

 the typical suture with the high median saddle of the siphonal lobe 

 and the saddles ending in phylloid points; although the number of 

 saddles and lobes is not larger than in the Indian specimen. 



The genus Perrinites is of great stratigraphical importance for 

 Texas, It has been found, so far, in the Clear Fork and in the middle 

 part of the Double Mountain formation of north Texas, and in the 



'Gemmellaro, Calc. c. Fusulina,' App., pi. A, fig. 3, 7. 



^Diener, Perm. foss. of the Central Himalayas, p. 115, pi. 5, fig. 20. 



