CRANIA FROM THE MOUNDS OF FLORIDA. 



439 



and many genera of Chiroptera. In all the anthropoid apes the lower premolars 

 exhibit two cusps and a large heel. In pteropine and gloosophagine groups of bats the 

 same peculiarities are seen, with the exception that the heel is of enormous size. 

 The commissural elements as a rule are marked, the post-commissure being larger 

 than the pre-commissure. The main contrast between the premolars of anthropoid 

 and those of Man consists in the fact that in the former the non-cuspidate portion is 

 larger than the cuspidate and the post-commissure is pushed back far from the cusps, 

 while in Man the non-cuspidate portion is nearly obliterated, the post-commissure 

 being brought up close to the cusps. 



It is a fact quite unexpected that the highest type of premolar — that is to say, 

 one in which the lingual cusp and the commissures attain the greatest development — 

 is found in the living subject and almost uniformly in low health conditions. 

 The best examples are met with in tuberculosis and congenital syphilis. 



(2). Cuspidation of lower molars. The plan of proceeding in the study of 

 the cusps of the lower molars is distinct from that of the upper. The divisions 

 between the cusps of the buccal and lingual sides of the crowns, and the commis- 

 sures at the anterior and posterior borders are sharply defined. 



I have found it convenient in taking notes to use numerals which indicates not 

 only the numbers, but the position of the cusps. Thus, in the arrangement \ it is 

 implied that there are two cusps on either side of the tooth centre. The number 

 above the interspace represents the buccal cusps and that below the lingual cusps. 

 The small zero mark represents the position of a commissural or annectant cusp. 



The number of examples of each kind of grouping is indicated in figures placed 

 above the fractions. We then have for fifty right first lower molars the following : 

 9 34 4 3 



The frequency with which molars are absent make it difficult to formulate 

 these cuspidations for equal numbers of teeth. 



I have instituted an inquiry at the Eastern State Penitentiary upon the teeth of 

 convicts, — the arrangement of the cusps and commissural cuspules being as here- 



with given. 



First lower molar 



- a t> • i x f Number of teeth 9 3443 



50 Right < -r, n r. ■ J , ■ o ,0 o oo 



51 Left 



( Formula of cuspidation 



1 



2„ 2° 

 2°- 



6 34 8 3. 



2 2° 2 2° 

 2 2 2 2°" 



Second lower molar 



59 Right j 



53 Left 



35 5 14 5. 



o 90 9 o° 

 2 2 2 2°* 



32 9 8 4. 



2 ''O o 90 



Third lower molar 



30 Right 

 [ 32 Left 



55 JOURN. A. N. S. PHILA.. VOL. X. 



I- ■ 



IS 6 6 5. 



2 2° 2 2° 

 2 2 2 2°' 



13 5 6 8. 



2 2° 2 2° 

 2 2 2 2°* 



