Permo-Carhoniferous Ammonoids of the Glass Mountains 109 



but are extremely numerous. On the inner whorl the ribs are very 

 prominent especially at the umbilical border where they develop al- 

 most a kind of tubercle ; they are also less inclined forward. In the in- 

 nermost whorls the ribs are practically radial, not very numerous, and 

 much more thickened at the umbilical border and on the lower part of 

 the flank. The interstices between the ribs have a rounded bottom and 

 on the outer whorl are narrower than the ribs while on the inner 

 whorls they are wider. The venter is entirely smooth. 



The septa are well separated from each other. The suture could not 

 be made out in its details, it being visible only on the interior side of a 

 half open whorl. It consists of a siphonal lobe, a lateral lobe and two 

 saddles. The siphonal lobe is undivided, as far as could be observed. 

 The lateral lobe is broad, rounded at the bottom and much wider above 

 than below. Both the saddles are rounded and entire; the external 

 saddle seems to be much narrower and higher than the first lateral 

 one. 



The internal sutures consist only of an undivided, funnel-shaped, 

 antisiphonal lobe and -a rather broad, high, rounded, entire internal 

 saddle. 



Dimensions : I II 



Diameter^ 16.8 mm (1) 12.8 mm (1) 



Width 3.2 0.19 2.8 0.22 



Height of the last whorl 5.8 0.35 3.5 0.27 



Diameter of umbilicus 6.6 0.39 5.7 0.45 



Relation to other species: 



P. multico status is very similar to P. Hoeferi Gemm.^ but in this 

 latter species the ribs are more sigmoidal and more numerous than 

 they are in ours. The Sicilian species is perhaps even somewhat more 

 evolute than that from the Glass Mountains. 



Very similar to our species is also P. Munsteri Gemm.,^ but the ribs 

 appear to be less numerous, especially on the inner whorls, and more 

 sigmoidal on the outer one ; it is also much more evolute. 



'There are fragments among our material which must have had a diameter of 

 at least 25 mm., or more. 



'Gemmellaro, Calc. c. Fusulina, p. 75, pi. 7, fig. 6-10; pi. 10, fig. 44-46. (Gemmel- 

 laro indicates in the text, fig. 1 and 2; while in the explanation of platei 10, he gives 

 the right numbers). 



'Gemmellaro, ibidem, app., p. 21, pi. D, fig. 17, 18. 



