14 PLEISTOCENE MAMMALIA. 
M. 2 is a considerably smaller tooth 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 shght cusps. Two roots support 
the outer portion of the tooth, a third and larger root the inner portion. 
(38). Permanent Dentition of the Lower Jaw of Canis 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 1. I and 2 have the root strongly laterally compressed 1. 3 
has it more or less triangular in section. Hach tooth has a somewhat chisel- 
shaped edge with a small accessory cusp placed externally to the main cone. 
C. 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, 1s a small single-rooted tooth with a simple 
conical blade, bearing, as a rule, a very shght 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 shehtly recurved. There is a shght 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.T. This is a large tooth supported by two stout roots. The anterior two 
thirds is formed by the powerful bilobed blade, the posterior lobe bee shehtly 
the larger and haying 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 les 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. 3, dc. 4, 
d.m, 2 = 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. 
' The description is drawn up from a made-up set of milk-teeth of Canis ? lupus from Torbryan, 
Torquay, now in the British Museum. 
