SKELETON IN THE. FLYING LEMURS. 153 



venous, and arterial foramina are all to be obsei-ved at their ordinaij 

 sites. 



As above remarked, Gynoceplmlus has a powerful mandible or lower 

 jaw. (Plate I, figure 2, and Plate II, figure 4.) Taken as a whole this 

 bone possesses a deep U-shaped outline, with the limbs of the body and 

 the rami rather more diverging in some specimens (1) than in others 

 (2, 3), where they may be quite parallel to each other anteriorly beyond 

 its ramal portion. In front the symphysis is strong, deep, and finuly 

 united, exhibiting a prominent mental process below, while its concave 

 inner surface is smooth. Beyond either ramus the body of the jaw is 

 thick from side to side, with its straight, upper, alveolar margin deeply 

 marked with the sockets of the various teeth, and its lower border, 

 parallel to it, rounded and smooth. The mesial line of the symphysis is 

 directed from below, fon\-ard and upward, at an angle of about 45° with 

 the imaginary mid-longitudinal line of the bone. The ramal portion of 

 either limb is considei'ably deeper than -the body, extending both above 

 and below it, being as a whole gradually turned outward from it at an 

 angle of 35° or more. Its outer surface is smooth and looks foi-ward and 

 outward, while its inner surface, also smooth, presents two conspicuous 

 ridges for the pterj'goidal muscles and is directed backward and inward. 

 Again, the oiiter surface is very moderately convex below, as compared 

 with the markedly concave inner surface. At the upper anterior margin 

 of this concavity we note the inferior dental foramen situated almost in 

 line with the alveolar border, at the base of the coronoid process, and 

 some 6 millimeters posterior to the last molar tooth. The angular border 

 is tliickened, circular in outline, and iinished off with a raised rim. 

 Externally and superiorily, the ramal portion is concave, that is, between 

 the coronoid and condylar process, a concavity that is gradually lost as 

 we approach the middle of the ramal area, or surface, upon this aspect 

 of the bone. 



The mental foramina, upon either side, a23pear to be three or four in 

 number-, a few millimeters apart, and all in the longitudinal line extend- 

 ing from a point opposite the second incisor to include the last premolar, 

 well within the lower border of the dentary portion of the jaw. Between 

 the base of the coronoid process and the last molar tooth there exists 

 a deep pit, the use of which can not here be determined, although in 

 life it probably harbors the tendon of insertion of the buccinator muscle. 



The coronoid process is, as a whole, situated above any other portion 

 of the mandible, being flattened from side to side, slightly thicker at the 

 base than above, and shaped like a cat's claw with the apex directed 

 backward. (Plate II, figure 4.) It is directed upward and outward at 

 an angle of about 45° with the transverse diameter of the condyle, from 

 which it is separated by a considerable interval. The axis of the condyle 

 is perpendicular to the median plane, its smooth articular surface extend- 



