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 Thylacynus 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. 
