﻿14 PLEISTOCENE MAMMALIA. 



M. 2 is a considerably smaller tootli than m. 1 but is constituted on the same 

 plan, having two relatively prominent cones or cusps on the outer part of the 

 tooth, and a depressed inner area bearing several slight cusps. Two roots support 

 the outer portion of the tooth, a third and larger root the inner portion. 



(3) Permanent Dentition of the Lower Jaw of Cauis lupus (PL V). — I. 1, 2 and 3 

 are all very similar teeth, differing only by their progressive increase in size, and 

 in the fact that while i. 1 and 2 have the root strongly laterally compressed i. 3 

 has it more or less triangular in section. Each tooth has a somewhat chisel- 

 shaped edge with a small accessory cusp placed externally to the main cone. 



(J. This tooth is of the usual type and differs from c. only in the fact that the 

 inner border tends to be rather more sharply curved. 



Pm. 1, which is sometimes wanting, is a small single-rooted tooth with a simple 

 conical blade, bearing, as a rule, a very slight cusp posteriorly placed. 



Pm. 2, 3, 4 are very similar two-rooted teeth each with a triangular blade, 

 which in pm. 3 and 4 may be slightly recurved. There is a slight cusp posteriorly 

 placed in pm. 2, and this becomes larger in pm. 3 and 4. The cingulum is well 

 marked on the inner surface of the teeth, and in pm. 3, and more often in pm. 4, 

 may give rise to a second posteriorly-placed cusp. In some cases each of these 

 teeth bears a slight cusp anteriorly placed. 



M. 1. This is a large tooth supported by two stout roots. The anterior two 

 thirds is formed by the powerful bilobed blade, the posterior lobe being slightly 

 the larger and having a small cusp placed postero-internally. The last third of 

 the tooth forms a depressed talon or heel and bears two cusps placed side by side, 

 the outer one being somewhat the larger. 



M. 2 is a rather small, somewhat oblong tooth supported by two roots. The 

 anterior part of the crown bears a pair of cusps placed side by side, while a third 

 cusp lies postero-externally. In some cases there are indications of a fourth cusp 

 placed postero-internally. 



M. 3 is a very small one-rooted tooth with a nearly oval crown bearing one or 

 more slight cusps. 



(4) Milk or Deciduous Dentition (PL V). 1 — The formula for this is d.i. f, d.c. \, 

 d.m. | = 28. 



The first permanent premolar has no milk predecessor. 



(a) Milk Dentition of the Upper Jaw. — D.i. 1, 2 and 3. These are all small and 

 extremely simple teeth with short crowns and long, somewhat tapering roots. 



D.c. is a reduced representative of the permanent tooth and requires no special 

 description. 



1 The description is drawn up from a made-up set of milk-teeth of Canis ? lupus from Torbryan, 

 Torquay, now in the British Museum. 



