Permo-Carhoniferous Ammonoids of the Glass Mountains 129 



thirty to the whorl, which begin at the umbiUcus but disappear before 

 reaching the external part. These elevations, which cannot very well 

 be called ribs, do not show on the shell of the larger whorls and can- 

 not be seen on every cast; but that depends probably on the stage of 

 preservation. The ornamentation of the shell is very characteristic 

 (pi. VI, fig. 61, 62, 68). It is composed of fine radial ribs flattened 

 on the upper surface which slants backward into a furrow and breaks 

 down steeply toward the front into the next furrow. The furrows 

 or interstices between the ribs are much narrower than these ribs 

 themselves. The ribs form a double curve on the flanks ; from the um- 

 bilicus they bend forward and from above the middle of the flank 

 they curve slightly backward and bend again forward until the shoul- 

 der of the ventral region, forming thus on the flank an S -hke figure. 

 On the shoulder of the ventral part they suddenly bend strongly 

 backward until the region of the sipho, thus forming a deep curve back- 

 ward on the ventral part. In smaller specimens the ribs are entirely 

 straight on the flanks but show also the deep backward curve on the 

 ventral portion. 



The suture (pi. VI, fig. 60, 66) could not be entirely made clear, but 

 enough of it could be traced to make sure of the generical position of 

 the species. The septa are not very near together; they never touch 

 each other. The siphonal lobe is divided in two branches by a high 

 siphonal saddle. Each of the branches is asymmetrical and bifid, the 

 inner point being much longer than the outer. The first lateral lobe is 

 bifid but shows an additional point at each side of the principal and 

 most prominent ones. The second lateral and the first and second 

 auxiliary lobes are trifid and symmetrical, while the rest of the lobes 

 on the flank, about five in number, seem to be funnel-shaped arid 

 to end in one single point; but these lobes could not be seen very 

 clearly. The siphonal saddle is moderately high, constricted below 

 the middle and notched at the top by a shallow indentation. The 

 saddles are all entire, high, relatively broad, rounded at the top, and 

 at least the external and the two lateral saddles are more or less con- 

 stricted near their base, while the auxiliary saddles are more tongue- 

 like, or are even only simple undulations. Their height decreases 

 steadily from the external saddle to the last auxiliary near the um- 

 bilicus. The internal sutures are unknown. 



