Permo-Carboniferous Ammonoids of the Glass Mountains 173 



broader. The auxiliary saddles are built after the plan of the second 

 lateral, but they lose first the lower pair of lateral branches and then 

 the upper, while the phylloid end becomes longer. The fifth auxiliary 

 saddle which lies on the umbilical wall is simple and entire. 



The internal sutures are not completely known, but the most impor- 

 tant part could be uncovered. The internal suture (pi. X, fig. 28) fol- 

 lows a slightly curved line. It is composed of the antisiphonal lobe, 

 two lateral and probably five auxiliary lobes with one internal, two 

 lateral and four auxiliary saddles between them. 



The antisiphonal lobe is divided into three branches by two high and 

 narrow secondary saddles, which lean considerably over toward the 

 median line of the lobe. The two lateral branches are much less deep 

 than the middle one, have two lateral indentations, and end in a long 

 and sharp point. The middle branch has two short lateral points, and 

 one long and sharp median point. The first lateral lobe is distinctly 

 trifid, the median point being longer than the lateral ones. It has one 

 secondary saddle on each side and is much narrower at the top than at 

 the base. The details of the rest of the lobes could not be observed but 

 they are probably similar to those of the first lateral lobe. 



The internal saddle is very narrow at the base and in the middle, but 

 ends in a very large phyllum which is a little higher than broad ; it has 

 one branch at each side, but these are of a different height ; it is curved, 

 bending over toward the antisiphonal lobe. The first lateral saddle is 

 similar to the internal but not curved, the phyllum in which it ends 

 being still a little longer with respect to the width than that of the pre- 

 ceding saddle. The following saddles are certainly built in a similar 

 manner, but the details could not be made out. 



Dimensions:^ 



I II III 



Diameter 47.6 mm (1) 25.5 mm (1) 23.7 mm (1) 



•Width 41.6 mm 0.87 721.5 mm 0.84 20.3 mm 0.86 



Height of last whorl 2^0.6 mm 0.43 11.5 mm 0.45 11.5 mm 0.49 



Diameter of umbilicus.... 8.7 mm 0.18 4.7 mm 0.19 - 4.8 mm 0.20 

 (between the shoulders) 



IV V VI 



Diameter 19.7 mm (1) 17.4 mm (1) 16.1 mm (1) 



•yyidth ., 17.6 mm 0.89 16.3 mm 0.87 14.4 mm 0.89 



^There are fragments of much larger specimens, one of which must have had a 

 diameter of about 100 mm. 



