SKCOXD OUTLIXK OK TKI'IT I'.KIiCULY Ml 



enables us to describe this molar as follows : It is of buno-selenodont 

 origin and has a complete protoloph and ectoloph, 1ml no ///</<'//'//. Its 

 homologies with the elements of the Anchitherium molar are clearly shown 

 by a comparison of Fig. 144 and Fig. 1GO. This illustrates again the 

 necessity of starting upon the trigonal basis instead of upon the basis of 

 two lobes, as in the work of French paleontologists. In his h'ur/nt.ine- 

 ments dv Monde An'mml, Prof. Gauclry has admirably worked out the 

 upper molars of the perissodactyla and artiodactyla from the sexitubercul.-n 

 stage onwards. He divides the tooth into two lobes, a " premier lobe," 

 including our protocone, protoconule and paracone and a " second 



FIGURE 43. 



No. 1. "Haplodont" or simple conical molars, the hypothetical starting point. 



2. Relations of haplodont upper and lower molars in the Dolphin. (The haplo- 

 donty of Dolphins may be secondary, see p. 190.) 



3. '' Protodont " lower molar of Dromatherium (p. 1!)), showing- main cone and 



accessory cuspules. 



4. Protodont lower molar of Microconodon (p. 19), accessory cuspules better 



developed and incipient heel or talonid. 



5. Progressive stages of " triconodont" inferior molars. Three cusps in line with 



"cingnlum" out-growths from the base (a) Amphilestes (inner face), (b) 

 Pkascolotherium (inner face), (<) Triconodon (inner face), (d) Amphilestes 

 (outer face) (p. 24). 



6. Triconodont inferior molars of a seal (Ogmorhinus). (Secondary, p. 143.) 



7. " Tritubercular " inferior molars of Menacodon ; () external, (b) internal view. 



The small cusps are internal to the protoconicl (p. 32). 



8. Tritubercular inferior and superior molars of Chrysochloris. In the upper ja\\ 



the apex of the triangle is internal, in the lower <'.ii>Tn<d (see also No. 10). 



9. " Tuberculo-sectorial " inferior molar of Amphitheriurn showing pointed-cusped 



"trigonid," and a low posterior, obtuse "talonid" or heel, an out-growth 

 chiefly from the base of the crown. The heel is " tubercular," functioning 

 as a pestle or crusher, the trigonid "sectorial," with cutting ridges and 

 piercing cusps (p. 27). 



10. (a-e) Typical tuberculo-sectorial inferior and superior molars. The talonid 

 bears three cusps "hypoconid" (hy d postero-external), "entocouid" (en' 1 

 postero -internal), " hypoconulid " (hl d posterior). Somewhat incorrect (see 

 Fig. 39). 



I I. Inferior molars of Miacis (a primitive Carnivore) showing in in.,, in., depression 

 of trigonid to level of talonid; all cusps now "bunoid" or f<>w and conical 

 (p. 84). 



12. Inferior molars of Anaptomorphus (primitive Primate) showing (in m :; ) 



degeneration of paraconid, elongation of hypoconulid (pp. 50, 158). 



13. A " quadritubercular " superior molar (Olbodotes, an Eocene Insectivore, or 



Rodent) showing three main cusps (pr, pa, me) with a fourth ("hypocone," 

 postero-internal) growing up from the cingnlum, changing the crown con- 

 tour from a triangular to a quadrate outline ; rudimentary "para," " meso," 

 and "metastyles" are present on the external edge of the crown (Fig. 104). 



14. Quadritubercular superior molar of an Eocene Primate Adapis (Fig. 132). 



I"). " Sexitubercular " superior molar of Notharctus (an Eocene Pi'imate) showing 

 the four main cusps (pr, pa, me, hy) with the addition of two small inter- 

 mediate conules "pi," "ml," also the well developed external parastylr. 

 mesostyle, and metastyle (Fig. 77). 



