Permo-Carboniferous Ammonoids of the Glass Mountains 151 



In smaller specimens the suture becomes somewhat simpler. In one 

 of a diameter of about 7.5 mm. we see that the flanks become very 

 flat and the ventral part very slightly rounded; between both a re- 

 markably sharp shoulder begins to appear. In this part the siphonal 

 lobe is still similar to that of the larger whorls, but the first lateral 

 lobe becomes entirely rounded (compare sutural line on fig. 58, pi. 

 VII) and does not show the two points as in the larger whorls. The 

 second lateral lobe still ends in one point but its upper part is here 

 wider than the middle portion. 



The first auxiliary lobe is entirely rounded, instead of being bifid, 

 and lies on the flat flank (compare sutural line on right side of fig. 

 57, pi. VII). The second auxiliary lobe nearly disappears and is 

 only indicated by a slight inflection of the outer flank of the first 

 auxiliary saddle. The second lateral lobe is much deeper than the 

 first lateral and the first auxiliary. 



The median saddle of the siphonal lobe (compare fig. 58, pi. VII) 

 is relatively lower than in the larger whorls. The external saddle is 

 high, broad, and well constricted near the middle. The first lateral 

 saddle is much narrower and lower than the external; it is not con- 

 stricted. The second lateral saddle is a little higher and much 

 broader and not constricted, while the first auxiliary is similar to the 

 second lateral in size and form. The second auxiliary saddle is only 

 indicated by a slight bulging of the outer flank of the preceding one. 



« 



Dimensions: 



H II III 



Diameter 23.2 mm (1) 14.6 mm (1) 13.7 mm (1) 



Width 18.0 mm 0.78 13.2 mm 0.90 12.7 mui 0.93 



Height of last whorl 9.8 mm 0.42 7.7 mm 0.53 6.9 mm O.-'iO 



Diameter of umbilicus ... . 2.7 mm 0.12 2.5 mm 0.17 2.2 mi>. 'j.l5 



IV V VI 



Diameter 11.5 mm (1) 10.9 mm (1) 8.7 mm .i) 



Width 11.2 mm 0.97 10.6 mm 0.97 8.7 mm 1.00 



Height of last whorl 5.1 mm 0.44 4.7 mm 0.43 3.8 mm 0.44 



Diameter of umbilicus. ... 1.8 mm 0.16 1.9 mm 0.17 2.0 mm 0.18 



Relation to other species: 



There is only one species nearly related to ours, that is V. irregulare 

 n. sp. The dififerences exist in the form of the inner whorls and in 



'Specimen I is slightly crushed, therefore the measurements may not be quite 

 correct. 



