138 



projecting from the socket is covered by cement. The length of the cement-clad root is 

 given in the figure of, I believe, the homologous tootli in Plate VII. fig. 1 4. 



The third premolar (p 3 ), also preserved in the specimen (Plate VII. figs. 1-3), is rather 

 larger in size, has a similar extremely low and slightly prominent crown, with the same 

 ridge running from the outer to the inner side, crossed by the shorter ridge at right angles 

 near the inner side of the crown, to which the longer ridge extends, leaving the shorter 

 ridge chiefly conspicuous behind it. The vertical extent of the cement-covered and 

 enamelled part of the second and third premolars projecting beyond their sockets does 

 not exceed 3 lines. This specimen resolves the doubt expressed with regard to their 

 empty sockets in the specimen figured in Plate XVII. p. 128 *, and demonstrates that each 

 socket contains its own small simply implanted tooth, and was not a division of a socket 

 lodging a larger two-fanged premolar. 



Beyond the third premolar the fore part of the crown of the maximized carnassial f 

 (Plate VII. figs. 1 & 2, p *) extends downward 10 lines. The shape, structure, vertical 

 grooving, and dimensions of this tooth agree with those in the specimens described in 

 the previous Sections. 



The trenchant margin of the upper carnassial is worn, as usual, obliquely from with- 

 out upward and inward, the cutting-edge of the enamel^being external (Plate VII. fig. 2, 

 p i). This edge does not run straight, but sinks to form alow angle at the end of a well- 

 marked external vertical groove (ib. o), marking off rather more than one-third of the hind 

 part of the crown, which answers to the similarly but better defined hind lobe of the 

 feline upper carnassial. The smoothly worn surface is thus divided into two parts, the 

 anterior one being broadest anteriorly at the thickest part of the tooth, while the pos- 

 terior gains breadth as it recedes toward the hind end of the crown. But the indica- 

 tions of resemblance to the feline carnassial, especially to that of Machairodus (Plate VII. 

 figs. 15, 16), do not end here. The inner surface of the crown, about one-fourth of the 

 way from the fore to the hind margin, projects and terminates in a ridge (v, figs. 2 & 3, 

 Plate VII.), which expands to the base of the crown, representing the more developed ridge 

 or vertical swelling of that part of the carnassial in Machairodus (fig. 15, v), from the 

 broadening base («/) of which the tubercle of the upper carnassial, wanting in Machairodus 

 as in Tliylacoleo, is developed in Felts. An opposite vertical ridge on the outer side of 

 the crown in Tliylacoleo (fig. \ , p 4, u) represents the most prominent part of the middle 

 lobe of the carnassial in Felines (fig. 16, u), whence the outer surface bends inward to 

 the angle or groove dividing that lobe from the hind one. The outer surface in Tliyla- 

 coleo bends in the same direction to the corresponding angle or groove (o, figs. 1 & 3), 

 then curves outward to the hind end of the crown. This is very low and subobtuse, as is 

 the corresponding end of the carnassial in Felines. But the fore part of the crown, in 



* " At the fore part of the carnassial socket the alveolar border is excavated by either a similar socket for a 

 two-rooted tooth, or by two contiguous sockets for two small'single-rooted teeth." 



t No evidence has yet been had that this or the antecedent permanent teeth had displaced deciduous prede- 

 cessors ; the adopted symbol p is to be taken with this reservation. 



