Permo-Carboniferous Ammonoids of the Glass Mountains 103 



venter. The cross section is more or less parabolical, much higher 

 than broad, the greatest width being found near the umbilical border. 

 Umbilicus practically closed. Ornamentation consists apparently only 

 of very fine lines that from the umbilicus curve strongly backward ; on 

 the upper part of the flank and on the venter no shell is preserved and 

 nothing can be said about the further course of these lines. The body 

 chamber is only partly known ; what is preserved of it has the length 

 of about one-third of the last whorl. 



The septa are well separated from each other. The suture (pi. V, 

 fig. 17, 18) forms a nearly straight line between the sipho and the 

 umbilicus. It is extremely simple, being composed only of a siphonal 

 lobe, a lateral lobe (a second one probably on the umbilical wall) and 

 two saddles. 



The siphonal lobe is extremely broad like that in Thalassoceras and 

 divided in two branches by a high median saddle. Each of the branches 

 is broad, and shows seven teeth at the bottom ; the size of these increases 

 from the sides to the bottom. The highest one can barely be distin- 

 guished. The first lateral lobe is narrow and about as deep as each 

 of the branches of the siphonal lobe and is a little less symmetrical 

 than the last one. It also has seven teeth at the bottom, but while in 

 the siphonal branch the largest one is practically in the middle, it is 

 nearer to the umbilical side in the first lateral lobe. A second lobe 

 which must be very small and which could not be made entirely visible, 

 must exist in the umbilical region. 



The median saddle in- the siphonal lobe is high, not very broad, 

 slightly notched at the top, a little broader at the base than above. The 

 external saddle is narrow, higher than the median saddle of the 

 siphonal lobe, and rounded at the top. The first lateral saddle is much 

 lower than the external saddle, but broader ; it is rounded from the base 

 up to the top, and its outer flank disappears in the umbilical region. 



Comparing this sutural line with that of Thalassoceras Gemmellaroi 

 Karp.^ we see that there is no essential difference between the two, but 

 that the suture of the typical Thalassoceras, as for example, Th. Phil- 

 lipsi^ or Th. suhreticulatimi,^ is entirely distinct through its digitate 

 lobes, which are divided into two dentate halves by a deeper indenta- 



'Karpinsky, Amm. d. Artinsk-Stufe, p. 80, fig. 3, a-d. 



''Gemmellaro, Calc. c. Fusulina, pi. 10, fig. 15 (not 12, as indicated in the text). 



'Gemmellaro, ibid., pi. 10, fig. 6. 



