672 



Bashford Dean Memorial Volume 



The transition between anterior (cusped) teeth and posterior (grinding) teeth is so 

 gradual that any division into two types must be somewhat arbitrary. However, of 

 the 33 rows of teeth on the upper jaw one might assign 19 rows to the anterior region, 

 leaving 14 (seven on each side) in the posterior region. In the lower jaw there are 32 

 rows of teeth of which 14 rows may be 

 assigned to the anterior region, leaving 

 18 (nine on each side) for the posterior 

 region. Thus there seem to be more rows 



Text-figure 12. 



Anterior teeth of a young Hetero- 



dontus phiUipi about 761 mm. (22.1 



inches) long: A, from the upper; 



B, from the lower jaw. 



After Maclay and Macleay, 1879, Figs. 18a 

 and 18b, p. 24. 



of anterior (cusped) teeth on the upper 

 jaw than on the lower (as in Striiver's 

 figure). In another specimen Maclay 

 counted 34 rows of teeth on the upper 

 jaw and 31 on the lower. The largest 

 number of rows of teeth noted by Maclay 

 on a lower jaw is not stated, but we infer 

 In Maclay's figures, as in Striiver's, the 

 each; but in Maclay's figure these are more 



^j^^j^M 



f7< 



^^^p/y 



*s. \> 



^f %^^^ '^hHb 







¥^ ^ 



"^Wm 



^^^ ' / 











•vj, 







f\ 





\ 





B 





-sl?^ 





i 



^■-^^^^ 





m 







W 



." 





w 



Text-figure 13. 

 Dentition of a very young (recently hatched) 

 female fieterodontus phillipi about 225 mm. 

 (8.8 inches) long: A, upper jaw; B, lower jaw. 

 After Maclay and Macleay, 1879, Figs. 14 and 15, pi. 24. 



was 36 on an upper jaw; the largest number 

 that it was less. 



anterior teeth of the adult have only one cusp 

 blunt as if worn by use. Maclay states that 



