Permo-Carboniferous Ammonoids of the Glass Mountains 117 



Similar to our species is also A. anceps Gemm/ from the Sosio beds 

 of Sicily. The ratio there is in a diameter of 17 mm. equal to i :o.65 : 

 0.59, while a similar specimen of ours (diameter 16.8 mm.) would have 

 1:0.67:0.61; but in the Sicilian species the umbilicus is much wider 

 (2 mm.). 



Still less similar is A. Suessi Gemm.^ likewise from the Sosio beds, 

 it being much more compressed and having a comparatively wide um- 

 bilicus. 



All these species show relatively strong transversal striae which are 

 not visible on any of our specimens ; but that Jiiay depend on the state 

 of preservation. 



Our species resembles somewhat A. ciscoense Smith^ but its or- 

 namentation seems to be much finer than that of the Carboniferous 

 species. The dimensions cannot very well be compared as there is only 

 a large specimen of A. ciscoense known, with a diameter of 35 mm., 

 which would give a ratio of 1:0.54:0.40. The umbilicus is entirely 

 closed, while in our species it would at that diameter certainly have at 

 least 1.5 mm. Also the sutures are different, A. ciscoense showing only 

 a small part of the fourth saddle. 



The somewhat doubtful Agathiceras texanum Girty^ has nothing to 

 do with our species; we shall discuss it a little more in detail in our 

 description of Agathiceras Girtyi n. sp. 



Age: 



Wolfcamp division, Permo-Carboniferous. 



Number of specimens examined: 

 More than one hundred. 



Locality: 



Immediately northwest of Wolf Camp, Glass Mountains. 



Agathiceras Girtyi nov. sp. 

 PI. VI, Fig. 27-46 



Shell subglobose, rounded on the flanks as well as on the ventral 

 side, very involute. Whorls numerous and deeply embracing, cross- 



"Gemmellaro, Calc. c. Fusulina, p. 79, pi. 7, fig. 20-22. 

 'Gemmellaro, ibid., p. 77, pi. 6, fig. 1-4; pi. 7, fig. 36. 

 'J. P. Smith, Garb. Amm. of America, p. 131, pi. 21, fig. 17-19. 

 *Girty, Guadalupian Fauna, p. 501, pi. 25, fig. 8. 



