74 THE GENERAL ANATOMY OF THE LEMUROIDEA [SECT. A 



In the temporal fossa the alisphenoid joins the parietal bone, 

 and thus the frontal and temporal bones are separated. 



On the inferior aspect of the skull, the palate is seen to be 

 much elongated : the glenoid fossa is so shallow as hardly to 

 merit that description : there is a well-developed post-glenoid 

 tubercle, and immediately behind this, a large foramen transmits 

 the primitive jugular vein from the endocranial cavity. The 

 external auditory meatus is shallow ; it is formed by an 

 " entotympanic " element 1 expanded in the form of a bulla, 

 enclosing the tympanic ring : the latter may be overlooked unless 

 carefully sought. The entrance to the carotid canal is in the 

 posterior wall of the auditory bulla, close to the medial side of the 

 stylo-mastoid foramen. 



The sutures between the pre- and post-sphenoids, and between 

 the latter and the basi-occipital bone as well as the metopic 

 (interfrontal) suture, persist in adult life. 



Most of the foregoing characters may be regarded as ex- 

 emplifying conditions of the kind termed " primitive " ; upon 

 such details of evidence the decision as to the position of the 

 Lemurs must finally rest. On the other hand, the presence of 

 a post-orbital bar (between the orbital cavity and the temporal 

 fossa) marks an advance on conditions otherwise primitive. 

 Again, the position of the entrance orifice of the nasal duct on the 

 facial surface (outside the orbit) might appear to be a lowly 

 character: yet it is regarded by some (ex. gr. Forsyth Major) as 

 a condition of specialization, determined by the enlargement of 

 the orbital cavity and lachrymal bone, in relation to nocturnal 

 habits. 



The upper median incisor teeth are separated by a wide interval, 

 and are two in number in each jaw on each side of the skull. On 

 each side (above and below) is one canine tooth. The lower canine 

 is so modified as to resemble an incisor, and the first lower 

 premolar resembles a canine tooth. The position of the latter 

 with regard to the upper canine tooth shews however that it 

 is really a premolar, for it is posterior to the upper canine, 

 whereas the true lower canine always comes in front of the upper 



1 Cf. Forsyth Major, Proc. Zool. Soe. 1899, and Kampen, Morph. Jahrb. 1905. 



