P ermo-C arhoniferous Ammonoids of the Glass Mountains 87 



crossed by a great number of lines of growth strongly inclined forward. 

 This gives them the aspect of twisted cord. 



In a larger whorl (pi. II, fig. 41) which must have had a diameter 

 of at least 50 mm., and which belongs to the specimen described im- 

 mediately above, the ornamentation changes again. The transversal 

 ri])s have disappeared entirely, the spiral ribs are very low, rounded 

 and broad. Another and still larger specimen (pi. II, fig. 42) shows 

 that there are sixteen ribs between the umbilical border and the ventral 

 shoulder and about seven or eight more between this and the sipho, 

 so that some of the spiral ribs must have disappeared too. They are 

 separated from each other by shallow interstices with rounded bottom 

 as wide as the ribs. 



The septa practically form a straight line and are well separated from 

 each other The external suture (pi. II, fig. 43-46) consists of the 

 siphonal lobe, two lateral lobes and two saddles. The siphonal lobe is 

 divided into two branches by a comparatively high tapering median 

 saddle, notched at the top. Both branches are very narrow in the 

 young individuals, but broader at the upper side in adults. The ex- 

 ternal saddle is high and narrow even in the adult specimen. The 

 first lateral lobe is long, tongue-shaped, well pointed and narrow, in 

 the younger individuals; but only a little less wide than the external 

 saddle, in adults. The first lateral saddle is much lower than the ex- 

 ternal one and also broader. The second lobe is on the umbilical wall; 

 it is broad, shallow, pointed, and funnel-shaped. 



The internal suture (pi. II, fig. 47) is known only in a small speci- 

 men (diameter, about 14 mm.) It consists of a funnel-shaped, not 

 sharply pointed antisiphonal lobe, a tongue-like internal saddle, a 

 first lateral lobe similar in form to the antisiphonal one, but a little 

 shorter, and a first lateral saddle about as high as the internal saddle, 

 but about twice as broad. 



Dimensions : 



I II III 



Diameter. . . .? 26.5 mm (1) 11,6 mm (1) 



Width 24.3 mm 13.4 0.51 7.3 0.63 



Height of last 

 whorl 28.2 11.6 0.44 5.0 0.43 3.5 0.41 2.4 0.39 



