CRANIA FROM THE MOUNDS OF FLORIDA. 437 



ing surface and actually tilt the tooth from its socket. The teeth themselves are 

 worn down horizontally in Esquimaux and Patagonians. According to Topinard, 

 the incisor teeth in North American Indians are disposed to be vertical, but there 

 are numerous exceptions that can be made to this statement. 



In the " wear" of teeth, not only do the degrees of wear aid in the determina- 

 tion of age, and not only does the amount of the loss of enamel and dentine give clues 

 (all things remaining equal) to the character of food consumed, but the details 

 in the patterns defined on the grinding surfaces themselves afford excellent charac- 

 ters in determining what the original arrangement of the cusps had been. 



The difference in the wear of teeth on the two sides of the jaw is conclusive 

 that the habit often favors certain parts of the enamel covering and throws undue 

 work upon other parts. In the elephant the molar on the left side may be alone 

 worn down. 1 Sometimes the left tooth appears to have been used in the main. 2 In 

 the living human subject I have often seen the teeth of the left side worn while 

 those of the right remain as sharply cusped as when they were erupted. If I am 

 right in assuming that a disposition exists for the lower jaw to push the maxillary 

 front teeth forward and the side teeth outward, when the force is expended more on 

 the front teeth than the side teeth, the upper jaw and palate become parabolic and 

 the jaw prognathous ; but if it is expended more on the side teeth than the front 

 teeth the form of the palate becomes hyperbolic, and the jaw orthognathous. 



(5). The cuspidation of the premolars and molars and the order of succession 

 of cusps. 



(1). The lower premolars. The skull No. 1,783 possesses a perfect set of 

 teeth which were but little worn. I desire to call attention to these teeth, since it 

 is likely that they represent the peculiarities of a people as ancient as any of 

 which we have knowledge on the American continent. 



The lower premolar exhibits a large outer and a smaller inner cusp. Indeed, 

 the term cusp for the elevation on the inner aspect of the crown is scarcely correct 

 since the enamel forms a mere lingule-like swelling about the base of the outer 

 cusp. Compare 1,060, Caucasian, and 430, Malay, p. 438. 



After making these inspections I became interested in noting the peculiarities 

 of the lower premolars, and herewith invite attention to some of the variations of 

 these teeth. The inner simple ring may become relatively large as compared with 

 the outer cusp. Compare figs. 73 and 79 second premolar. Or the inner ring- 

 becomes marked by one or more rounded swellings (beginnings of which are seen 

 in figs. 73 and 79) which appear in the depression between the outer and inner 

 parts of the tooth. Compare fig. 126, and the second premolar in fig. 76. Or the 

 inner margin of the tooth is cleft between these mammillations. Compare figs. 98 

 and 118. 



A somewhat distinct class of variations is noted in the crown. The general 

 character is that, indeed, of a true premolariform variety. The inner border is dis- 



1 Owen, Odontography, pi. 4. 



2 Ibid, pi. 14. 



