Permo-Carboniferous Ammonoids of the Glass Mountains 73 



on the keels of the venter they cause sUght tubercle-like swellings. 

 While four-fifths of the flank (counted from the umbilicus) is quite 

 flat, the shell bends suddenly over to the venter from the spiral line 

 where these ribs begin to appear. Farther inward the ribs get shorter 

 but yet stronger, and the keels form rows of well-marked tubercles, 

 which are visible on the cast (pi. I, fig. 45, 45a). 



The septa are not mUch separated and the lateral lobes and saddles 

 even nearly touch each other. The suture follows a sigmoidal line. It 

 consists of a great number of saddles and lobes in the description of 

 which we adopt the nomenclature established by Noetling (compare 

 text figure i, and pi. I, fig. 41). 



The siphonal lobe (S) is very deep with parallel sides and extreme^' 

 narrow. It occupies the width of the median groove on the venter and 

 ends in two points. The two lateral lobes, Li and L2, are divided in 

 two branches, the first lobe being symmetrical, the second nearly so. 

 The first lateral lobe is much deeper than the siphonal lobe ; the second 

 is deeper than the first lateral lobe. On the flank there follow still ten 

 auxiliary lobes, the last of which lies on the umbilical shoulder. At 

 least the first five auxiliary lobes are divided into two branches by a 

 high median saddle but also in the rest we find at least such a division 

 indicated with the possible exception of the last one^ which seems to be 

 rounded. The fourth auxiliary lobe is very asymmetrical, the branch 

 nearer to the umbilicus being much larger than the other one. The last 

 two auxiliaries are somewhat dim, and could not be represented in our 

 figur.;. 



The external saddle is divided into two unequal parts, Esi and Es2 

 by the adventive lobe A. The part Esi, which is nearer to the sipho, 

 is high and asymmetrical; it is deeply scalloped by four rudimentary 

 adventive lobes on the siphonal side and five more on the umbilical side. 

 These latter five lobes are much deeper than the other four and conse- 

 quently the rudimentary adventive saddles between them are much 

 longer and more slender than those on the siphonal side which are 

 short and rounded. The eighth rudimentary adventive lobe («0 is 

 divided by a low median saddle; the first seven are simply rounded at 

 the bottom, while the ninth is strongly curved. The branch Esi is 

 slightly notched at the top. The other branch of the external saddle 

 Es2 is much smaller and forms an angle of some 30° with the main 



