126 University of Texas Bulletin 



and the internal sutures cannot be studied; and we had to show that 

 there is an external character which can generally be observed and at 

 the same time is absolutely reUable. 



We see that our species shows the characteristic median saddle and 

 siphonal lobe of Adrianites and that the number of its lobes is larger 

 than in Agathiceras, although the general character of the lateral 

 lobes and saddles is the same ; consequently, there is no room for doubt 

 that our species is a typical Adrianites. 



Relation to other species: 



The only species which is very nearly related to ours is Adrianites 

 insignis Gemm./ but it is still relatively broader and the sutural line 

 has one saddle more than ours. A certain similarity exists also be- 

 tween our species and Adrianites elegans Gemm.^ but this species is 

 somewhat higher than ours and more rounded on the ventral part. The 

 sutural line is more strongly curved than in ours, but has the same 

 number of lobes and saddles. The ratio of diameter to width, height of 

 the last whorl, and diameter of umbilicus is, in the smallest of Gemmel- 

 laro's specimens, i :o.6 10.45 -O-^S ; which shows that the width is re- 

 latively less, and that the umbilicus is much larger, than in our species. 



Much more similar is the ratio in Adrianites insignis, which, ac- 

 cording to the measurements given by Gemmellaro, is i : 0.87 : 0.48 : 

 0.12. These are nearly the same as those of our species; i. e., i : 0.79: 

 0.47: 0.12. 



There has been another very broad species described — Adrianites 

 Stuckenhergi Karp. sp.^ — which has about the same number of lobes, 

 but its external form is entirely different. 



G. Boehm* has described a very broad form of Adrianites under the 

 name of Adrianites timorensis, but it is easily distinguished by its 

 wider umbilicus. 



Age: 



Word formation, Permo-Carboniferous. 



'Gemmellaro, loc. cit., p. 42, pi. 6, fig. 8-10. 



^Gemmellaro, loc. cit., p. 41, pi. 6. fig. 14-17; pi. 7, fig. 23, 24. 



'Karpinsky, Amm. d. Artinsk-Stufe, p. 65, pi. 5, fig. 4, a-e. 



*G. Boehm, Jiingeres Palaeozoicum v. Timor, p. 321, pi. 11, fig. 3, a-c; text, fig. 1 a, b. 



