VEETEBEATA 111 



The Glires are found in the strata of all regions, but in 

 reduced numbers in the Eocene in all countries except 

 temperate South America, where they were abundant at 

 that age. There are four suborders, which differ as fol- 

 lows : 



I. Fibula not articulating with calcaneum ; ankle and 

 elbow not toogued and grooved ; one pair of incisors 

 in upper jaw. 



Incisive alveolus not passing|into centre 

 of ramus of lower jaw ; fibula dis- 

 tinct ; Hystricomorpha. 



Incisive alveolus penetrating ramus; fibula 



distinct ; Scinromorpha. 



Incisive alveolus penetrating ramus ; fibula 



coossified with tibia ; Myomorpha. 



II. Fibula articulating with calcaneum ; ankle and el- 

 bow tongued and grooved ; two incisors in upper 

 jaw. 



Inferior incisor penetrating ramus ; fibula 



and tibia coossified ; Lagomorpha. 



The Hystricomorpha ( porcupines , cavies, etc. ) are 

 abundant in the Eocene of South America, and are pres- 

 ent in the Upper Eocene of France. They are more 

 abundant in the Neocene of South America and France, 

 and are present in the Upper Neocene of North America. At 

 present they are cosmopolitans, excepting Australia, but 

 they chiefly abound in South America. (Fig. 47.) The 



