318 DR. A. SMITH WOODWARD OX THE [Dec. 1914, 



The bone is remarkably stout, and the symphysis, so far as 

 preserved, is as heavy as that in the mandible described by G-audry. 

 As well shown in upper (PI. XLIV, tig. 1) and lower (PL XLIV, 

 fig. 4) views, the right ramus is broken away a little to the right of 

 "the median line ; and, as seen in inner view (PL XLIV, fig. 2), the 

 upper ledge of the symphysis is partly obscured by hard matrix. 

 The inner face of the mandibular ramus is accidentally indented by 

 crushing in the lower part, but the symphysis evidently retains its 

 original shape. The smooth. bone bears no clear mark of the floor 

 of the mouth (mylohyoid muscle), but the limits of the insertion 

 of the large digastric muscles are distinct (PL XLIV, fig. 4, and 

 text-fig. 1b, p. 317). The surface for the digastrics (<:?.), which 

 is divided in the middle line by a slight ridge, truncates the lower 

 border of the symphysis obliquely, being directed both backwards 

 and downwards; and the vertical thickness of the muscle at 

 this insertion must have been scarcely less than 10 mm., or at least 

 a quarter of the maximum depth of the jaw. From the anterior 

 border of the digastric insertion the plane of the outer face of 

 the symphysis inclines upwards abruptly, without any horizontal 

 extension below (PL XLIV, figs. 2 & 4). Above the posterior border 

 of the digastric insertion the inner face of the symphysis is 

 impressed with the usual deep pit (PL XLIV, fig. 5), in which the 

 two ovoid hollows for the origin of the geniohyoid muscles are 

 seen. Above this again the inner face of the symphysis rises 

 sharply, but soon turns forward into the long ledge sloping upwards 

 to the front teeth. As shown in the broken section (PL XLIV, 

 fig. 2), the cancellous tissue of the bone is of very open texture, 

 and the outer dense wall appears to be unusually thin. 



The horizontal ramus of the mandible of Dnjopithecus, with its 

 symphysis, is therefore well known, and the two opposing views as 

 to the systematic position of this Ape may now be reconciled 

 in the light of recent researches. In. his original description, 

 Lartet considered that the apparent shortness of the jaw implied a 

 face more nearly human than that of the existing Anthropoids, and 

 he pointed to other features which suggested some approximation 

 to Man. Graudry, on the other hand, after studying a better- 

 preserved specimen, decided that Dryopitliecus was the lowest of 

 the known Apes, and even approached the Macaques in the shape 

 of the mandibular symphysis. 



If the transverse section of the mandibular symphysis of 

 Dryopitliecus (text-fig. 1 b) be compared with that of the nearly 

 contemporaneous Macaque, Mesopithecus (text-fig. 1a, p. 317) . a 

 striking resemblance will indeed be noted. There is the same 

 abrupt upward slope of the anterior face of the bone, and although 

 the digastric insertion (dotted in the figure) is relatively smaller 

 in Dryopithecus than in JMesopithecus, it is still very large for 

 an Anthropoid. The digastric muscles in Macaques and other 

 Monkeys are, in fact, excessively developed to undertake some 

 of those functions of the floor of the mouth that are performed 

 by the mylohyoid and geniohyoid muscles in the large existing 



