ii6 



University of Texas Bulletin 



Dimensions: 



I 



Diameter 22.0 mm (1) 



Width 14.0 mm 0.64 . 



Height of last whorl.... 13.6 mm 0.61 



Diameter of umbilicus. ... 1.0 mm 0.045 



IV 



Diameter 14.8 mm (1) 



Width 10.1 mm 0.68 



Height of last whorl 9.1 mm 0.61 



Diameter of umbilicus .... nearly closed 



VII 



Diameter 11.8 mm (1) 



Width 8.7 mm 0.74 



Height of last whorl.... 6.6 mm 0.56 

 Diameter of umbilicus. . . . nearly closed 



X 



Diameter 8.0 mm (1) 



Width 6.0 mm 0.75 



Height of last whorl.... 4.4 mm 0.55 

 Diameter of umbilicus .... nearly closed 



XIII 



Diameter 5.2 mm (1) 



Width 4.1 mm 0.79 



Height of last whorl 2.7 mm 0.52 



Diameter of umbilicus . . . nearly closed 



II 

 18.0 mm (1) 

 11.7 mm 0.65 



11.0 mm 0.61 

 nearly closed 



V 



14.3 mm (1) 



10.1 mm 0.71 

 7.8 mm 0.55 



nearly closed 



VIII 



10.6 mm (1) 

 7.8 mm 0.74 

 5.8 mm 0.54 



nearly closed 



XI 



7.6 mm (1) 



5.7 mm 0.75 



4.1 mm 0.54 

 nearly closed 



XIV 



2.6 mm (1) 



2.2 mm 0.85 



1.3 mm 0.50 

 nearly closed 



III 



16.8 mm (1) 

 11.3 mm 0.67 

 10.2 mm 0.61 

 nearly closed 



■ VI 

 12.6 mm (1) 



8.8 mm 0.71 



7.0 mm 0.56 

 nearly closed 



IX 

 8.2 mm (1) 

 6.2 mm 0.67 

 4.5 mm 0.55 

 nearly closed 



XII~ 



5.9 mm (1) 

 4.5 mm 0.76 



3.1 mm 0.53 

 nearly closed 



Relation to other species: 



Our species is distinct from every other that has been described. 

 In its outer form' it resembles most A. cfr. uralicum Karp.^ from the 

 upper Carboniferous of Russia, but that species is still more compressed 

 than ours. By taking the dimensions from the figure we get diameter 

 I, width 0:56. height of the last whorl, 0.51 ; while at that same height 

 the ratio in our species would be 1 10.65 :o.6i. The type of A. uralicum. 

 Karp. from the Artinsk shows a much greater difference. If we take 

 his specimen with a diameter of 23. mm.^ we find the ratio of i :o.54: 

 0.61, while our nearest specimen with 22 mm. diameter has the ratio 

 I :o.64: 0.61. The umbilicus is nearly closed in A. uralicum as wtell 

 as in ours. The ornamentation of the Russian form is probably a little 

 coarser than in ours. 



^Karpinsky, Amm. d. ArtinsknStufe, pi. 4, fig. 4, b, c, d. 

 =Abich, Djoulfa, p. 120. 



