236 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 83 



Lingually the body of the bone shows very interesting features. 

 Beginning from above in the incisor and premolar region, the bone 

 slants inward and downward, and a marked incHned shelf is formed 

 that reaches, gradually diminishing, to the molar region. The lower 

 border of this shelf, when looked at from below, constitutes a marked 

 ridge that extends all along to behind the last molars ; and underneath 

 this border is a distinct continuous groove extending bilaterally from 

 the symphysis to considerably behind the M3, where it shallows out 

 somewhat and merges with the pterygoid fossa of the ramus. There 

 is no trace of a vertical symphyseal ridge or of any distinct anterior 

 fossa above the epimedial ridge ; but below this ridge is a low triangu- 

 lar elevation merging with that of the glenoid tubercles, which, in 

 a measure, subdivides the submedial groove into left and right 

 portions, with a somewhat more marked depression on each side of 

 the median line. Such a complete epimedian ridge, with such a distinct 

 and practically continuous submedian antero-posterior groove, is not 

 equalled in any of the other ancient jaws, and is represented only in 

 occasional traces in modern man. The epimedian ridge in the Ehrings- 

 dorf specimen is directly, and without any mark of junction or 

 interruption, continuous with the mylohyoid ridge. But little can be 

 said about the lingual surface of the ramus ; what there is may be 

 duplicated in every particular in modern jaws. 



The prospective or advanced characters of the jaw are, therefore, 

 its slight true symphyseal recession ; its distinct mental eminence ; the 

 modern forms and in the main also the size of the teeth ; the markedly 

 diminished third m.olars ; and in general the characters of the ramus. 

 Features in which, on the other hand, the jaw approaches those of 

 apes, are especially the upper lingual shelf with the anterior submedial 

 fossa below it ; the relative narrowness of the teeth ; the general shape 

 and relative dimensions of the body of the bone and the dental arch ; 

 and the flattening from side to side of the precanine region, this 

 being a remnant of the early human and prehuman powerful de- 

 velopment of the roots of the canines. 



THE LOWER JAW OF THE CHILD 



The specimen is marked by its stoutness (thickness of body at 

 Mi, 16.5 ; at symphysis, 16 mm.) ; by its flat and moderately receding 

 symphyseal region with a very slight but distinct chin eminence ; 

 by a U-shaped dental arch ; by the relatively narrow molars ; and by 

 a broad and high coronoid process. It was probably the jaw of a 

 male child. 



