OBJECTIONS AND DIFFICULT! KS AM) OTIIKI! THKnlilKS 



209 



side the lower molars, and the future antero-internal cone (protocone) 

 was developed as an internal shelf acting as a mortar for the cusps of 

 the lower teeth and at a much later period developed a cusp. The 

 hypocone arose in a similar way with the elongation of the teeth. . . . 

 In the Centetidce and Peralestes, the upper molars could not have over- 

 hung the lower ones to the same extent, consequently no internal lobe 

 bearing the protocone was developed and the external cingulum was 

 very largely developed." Thus Woodward's position agrees in the main 

 with the views recently put forward by Gidley mi pal;eontological 

 grounds (p. 219). 



The author therefore accepts the tri tubercular theory from the Eocene 

 period onwards, but endeavours to establish another theory as to the 



. p /r-s.a 

 -'-';:&'* 



Fio. 203. Transverse section of the germ of the first upper molar of a young Mole 

 "showing the primitive dentine germ giving rise to the paracone (5)," the protocone appearing 

 as an internal extension or talon from the base of the paracone, which is hence supposed by 

 Woodward to be the most ancient portion of the crown. The dental lamina dl on the lingual side 

 of the developing true molar may represent the vestiges of a post-penn-ment //i 1 . ,< >-. After 

 M. F. Woodward. 



origin of the superior tritubercular type; he excludes the triconodont 

 and protodont stages, unless we suppose that the anterior cusp 

 disappeared. 



As regards embryological testimony, he first refers to the papers of 

 Rose on the human teeth. Tucker on the teeth of Ungulates, and Leche 

 on the teeth of Marsupials, as concurring in the demonstration that ///> 

 paracone (of Osborn) ?.s tin: jirf <-nsp to </rrrlop in 1h< vpj.>i ,' nmlur fn-fii. 

 He continues ((yy //'/.. p. .~>S,~>) from his own researches upon the relatively 

 primitive Insectivora, " If the protocone represents the summit of the 

 original protodont tooth of the ancestor of the Mammalia it must lie the 

 direct continuation of the primitive dentinal germ, and as such should be 

 found to develop in a line with the axis of that structure. That this is 

 not the case is well seen in Fig. 32, PI. XXVI. [Fig. 203], where the 

 paracone is found to be identical with the primitive dentinal germ, and 



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