10 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.67 



through an open wound. It is certain that this occurred when the 

 animal was less than half grown, or probably very young. 



The injury immediately caused a profound alteration in the mech- 

 anism of the lower jaw. As fully half of the bone upon the left side 

 measuring from the last molar to the condyle, was lost, there was no 

 articulation between the mandible and that side of the skull, and the 

 only motion possible was a sort of rotation of the lower jaw. It is 

 certain, of course, that the mouth could be opened sufficiently for the 

 insertion of required food, but it is hardly likely that possible move- 

 ment was sufficient to enable the animal to use its canines for any 

 practical purpose. The lower canines to some extent, and the upper 

 ones especially, are developed in length well beyond what is normal 

 In this genus. The mandible is further characterized by a stunted 

 or infantile condition of the left ramus, which results in an abnormal, 

 crowded position of the third molar upon that side. The balance of 

 the asymmetry exhibited by the mandible is due to the more normal 

 growth of the right ramus and the twisting effect exerted, through 

 the teeth, by the maxillary deformities. 



In considering the form of the skull proper it must first be remem- 

 bered that the insertions of the left pterygoid muscles have been totally 

 destroyed, and those of the left temporal and masseter, largely so. 

 To just this extent are the effects of these muscles upon the skull 

 destroyed, except as there may have been fractional, aberrant functions 

 through chance secondary attachments. 



The supraorbital ridging and the relational position of the two 

 orbits may be said to be the only symmetrical part of the skull The 

 occipital plane also shows practical symmetry, although the basioccip- 

 ital does not. 



The growth of the right side of the skull has been as nearly nor- 

 mal as the limitations of the left side would permit. This has re- 

 sulted in a disproportionately swollen appearance of the right side 

 of the cranium, and in a sharp twisting of the face to the left. A 

 somewhat fantastic, though expressive, way of describing the present 

 eft'ect is to imagine the juvenile skull as having been made of soft rub- 

 ber, held rigid in the vicinity of the left zygomatic process of the 

 maxilla, and the rest of the skull then inflated and expanded. This 

 appearance, as previously mentioned, has been attained through 

 nongrowth of the left side. All parts of this side have remained 

 infantile, especially the length of the zygomatic arch, which has ensued 

 upon the virtual destruction of functions of the muscles of mastica- 

 tion upon the left side. 



One result of the infantilism of the maxillary border upon the left 

 was the failure of the alveolar row to increase in length, with the 

 consequence that insufficient room was provided for the normal em- 

 placement of the permanent first molar. This has resulted in the 



