120 University of Texas Bulletin 



All the species from the Russian Artinsk and the Sicilian Sosio beds 

 are much more compressed on the flanks and do not show more than a 

 general generic resemblance. The only exception is A. Krotozvi Karp.^ 

 which is much broader than our species, and has an entirely different 

 cross-section and a much wider umbilicus. Its suture line also shows 

 a much lower fourth saddle. 



The species from the upper Carboniferous of America (A. ciscoense 

 Smith) and of Russia {A. civ. uralicum Karp. ) are much more com- 

 pressed on the flanks. 



Girty^ has described an Agathiceras texanum^ and this species must 

 be of some interest to us as it comes from a horizon about synchronical 

 to the one in which our species has been found. It is difficult to com- 

 pare both forms as Girty does not figure the aperture nor the ventral 

 part: as no dimensions are given a comparison is nearly impossible. 

 The general form seems to resemble that of our species, but the umbil- 

 icus is certainly wider. Entirely different is the suture line, which in 

 A. texanum is curved, and consists of only three saddles. The orna- 

 mentation is also certainly different, but its details are not made very 

 clear by Girty's description, although he refers to Adrianites Stuck- 

 enbergi Karp, as having a somewhat similar one. 



The generic position of A. texanum is extremely doubtful. The 

 form of the second lateral saddle is different from anything I have seen 

 in typical Agathiceras, and there exists evidently one saddle less than 

 in the type of the genus. Girty cites A. Krotozvi Karp. as having also 

 one saddle less than the type, but Karpinsky says only that the aux- 

 iliary or umbilical saddle is narrow and in his figure 7-c, it is clearly 

 shown, while in Girty's species the next saddle seems to belong to the 

 internal suture. 



Age: 



Word formation, Permo-Carboniferous. 



Number of specimens examined: 



More than fifty. The species is one of the most common at the 

 different localities. 



'Karpinsky, Amm. d. Artinsk-Stufe, p. 66, pi. 5, fig. 7. 

 ''Girty, Guadalupian fauna, p, 501, pi. 25, fig. 8 and 8-a. 



"Girty changes the name into Agathoceras, hut I cannot see a reason why that 

 should be done. , 



