536 Dr. ©. I. Forsyth Major on the 
metacone, which in Centetide continually advances further 
inwards, gradually replaces in function the “ protocone” 
(talon), which in consequence becomes superfluous. In the 
interpretation of the homologies the two have been pretty 
generally confounded with each other, 7. e. paracone + meta- 
cone is regarded as the ‘ protocone.” 
As I would finally point out yet once again, the three 
main cusps of the crown—upon which the theory of the tri- 
tubercular form of the dentition of Centetidee is based—accord- 
ingly consist externally of the two most strongly developed 
of the outer cusps, the parastyle and metastyle of Osborn, and 
internally (apex of the triangle) of the paracone+metacone, 
united to form a single cusp. In cases where similar forms 
occur among the Lemuride the two outer cusps are consti- 
tuted by the paracone and metacone. Like Winge, I have 
interpreted * the apex in Lemuride as being homologous with 
the “ protocone”’ of other mammals—Winge’s 6. 
With regard to the lower molars I can express all that I 
need to say here in a very few words. A characteristic 
feature in these teeth is the extensive reduction exhibited by 
the “talon,” which usually appears only as a low posterior 
basal cusp. The lower molars, therefore, essentially consist 
of the anterior trigon (Osborn’s “ trigonid”’) alone. When 
we consider that the talon (Osborn’s “ talonid’’) is developed 
to the fullest extent among mammals belonging to the Lowest 
Tertiary | and Upper Cretaceous | Beds, it appears, in con- 
nexion with all that has been stated above in the case of the 
upper molars, unjustifiable to wish to regard the form of the 
lower molars in Centetide as of a primitive type. 
Il. The Antemolars. 
Leche remarks § with reference to the upper incisors and 
canines of Centetide (Microgale, Hriculus, Centetes), that 
they are provided with accessory cusps more abundantly in 
specialized and forms a parallel to Centetide, and still more to Chryso- 
chloride, that this fusion likewise occurs in all molars; the protocone in 
Notoryctes is still developed to a considerably greater extent than in 
Centetidee. 
* “On Megaladapis &c.” (vide supra), p. 28, text-figs. 1 and 2. 
+ Cf. Lemoine, “ Etude d’ensemble sur les dents des Mammiféres 
fossiles des environs de Reims,” Bull. Soc. Géol. de France, 8° série, 
t. xix. 1891, pls. x., xi. 
t Cf. H. F. Osborn, “ Fossil Mammals of the Upper Cretaceous Beds,” 
Am. Mus. Nat. Hist. vol. v. art. xvil. (New York, 1893), pl. viii. 
figs. Hl, Al. 
§ Anat, Anz. xiii. p. 520. 
