336 



PATAGONIAN EXPEDITIONS '. PALAEONTOLOGY. 



4. Lachrymal spreading out on the 

 face. Lachrymal duct within 

 the orbital rim. 



5. Antero-posterior shortening of 

 basis cranii. 



6. The mandibular angle is strong- 

 ly inflected. 



7. An alisphenoid bulla present in 

 some genera, absent in others. 

 Tympanic annular and unfused 

 with the adjacent elements in 

 genera with bulla, unknown in 

 those without alisphenoid bulla. 



8. Basisphenoid perforated by in- 

 ternal carotid artery. 



9. Posterior extension of the malar 

 bar to form the preglenoid 

 process. 



4. In most marsupials the perfor- 

 ation for the lachrymal duct is 

 either on or external to the or- 

 bital rim. In Tliylctcynus and 

 in some specimens of Borhycena 

 there are perforations both with- 

 in and without the orbit. The 

 facial expansion of the lachry- 

 mal is common to marsupials 

 and also to a number of the 

 Creodonta and Insectivora. 



5. Characteristic of carnivorous 

 marsupials. 



6. Mandibular angle more or less 

 strongly inflected in all marsu- 

 pials except Tarsipes. This 

 character is also developed in 

 some of the Insectivora and in 

 Creodonts of the Mesonychid 

 phylum. 



7. The alisphenoid bulla is a mar- 

 supial-insectivore character. 



8. Characteristic of the Marsupialia 

 and Monotremata. Acrobates 

 Pygmceus is exceptional in lack- 

 ing this perforation, the internal 

 carotid entering the skull through 

 a foramen between the petrosal 

 and the basisphenoid (Weber, 

 Die Saugetiere, p. 46). 

 9. A marsupial character. 



