Vol. 70.] 



LOWER JAW OF AX AXTHItOPOLD APE. 



317 



(m. 1) measures only 10 mm. in length, and is somewhat narrower 

 than the others, with a relatively prominent antero-internal cusp 

 (metaconid). The second (?/?. 2) and third (m. 3) molars measure 

 11 mm. and 11*5 mm. in length respectively, and the third tapers 

 a little behind where the posterior cusp (mesoconid) is relatively 

 large. Of the fourth premolar it can merely be stated that 

 the roots prove it to have been as large as the same tooth previously 

 described in Dryojntliecus font an i '. 



Fig. 1. — Cross-sections of the mandibular symphysis in 

 various Primates ; two-thirds of the natural size. 



a. Adult Mesopithecus. b. Adult Dryopithecus. c. Adult Homo heidel- 

 bergensis. d. 1 Very young- Chimpanzee, with (d-) young- adult and (d 3 ) 

 adult female of the same. E. 1 Very young Gorilla, with (e 2 ) adult female 

 and (e 3 ) adult male of the same. r. Adult Eoo.iithropv.s dawsoni. 



[The dotted border marks the insertion of the digastric muscle, and the thick 

 black border the origin of the geniohyoid.] 



