ON THE STRUCTURE AND CLASSIFICATION 
, , fi T8 this has five molars with the somewhat doubtful topression 
in I’l. I, ftg. vonvpsented by Professor Owen, in figure .34, 
of u sixth : second, the ramus^^ premolars and one molar well 
with two incisor imprcssioi . , „py„j.al succeeding molars. There are two 
preserved, with the J^ese fragments together as represented 
chief grounds to jus y _ They naturally involve the 
in figure 1, the anteno e character of the premolars, 
r,„estio„ofthem„hrrformu a.andjfJhe^^^^^ 
and need therefore o h f^J^ impressions of pw, and pm„ 
Professor Owen (fig- • )y besides impressions of four others mi, 
, 'r fi„ o. and show conclusively: (a), that the premolars were 
llralyT^re the molars’; (h), that there were six molars and four ^molars; 
second the specimen figured in fig. 33 (Mes. Mamm.) confirms the above, as . 
h.clud;s two Lisors, a canine and ten teeth behind it. This result differs from that 
readied hv Professor Owen.* • ei ; 
There were at least three moi«,r, (p. 26, Mes. Mamm.) ; two of them, and ,,, 
are represented hv distinct impressions which indicate that they were compactly placed, 
with |H.inte<l rci urved crowns. In figs. 33, 40, 41 (Mes. Mamm.) the lateral mcisor 
is er(*et. 'I'hese teeth and the rather slender recurved canine resemble the correspond- 
ing teeth in Trirnnnthm, rather than those in the AmhJotherium or StyMon series. 
Tlie online is nitlicr slender, vertical, recurved at the summit, and apparently bifanged. 
'fhe premohirH liave tlic typical number, four, and increa,se in size antero-postenorly. 
'I'he crown is implanted by two fangs, with a convex anterior and concave posterior 
8loiK>; tlie cingulum forms an anterior basal cusp, but extends slightly below 
the jKisterior liasal lu'el, which is unusually prominent. The molars are very 
unique in pattern : they present three cusps, the anterior and posterior cusps being 
rotnteil inwards. The outer surface presents a high vertical and symmetrically 
eonv<>x main cusp, with a faint cingulum near the base ; from its anterior and 
posterior sloiies project tlie lateral sub-equal cusps which are confluent below with 
the general ronvexity of the crown ; on the inner aspect these cusps are seen to be 
rotated inwards and to spring in part from the shelf-like plane surface of the crown 
a.s two cones with widely divergent apices. The shelf at the base of these cusps 
may lie considered either as a broadened cingulum, or as a wide cusp-bearing 
base, such as is seen in some primitive bunodont molars, e. g. Palceochoerus. The 
• The prcinolars are correctly represented in figs. 35 and 36 ( Mes. Mamm., PI. I), and conform with my 
drawing. In figs. 33 and 34 they are incorreatly drawn, as shown by comparing them with the impre-sions 
of four recurved premolar tips in fig. 33 (No. 46019). Part of the figures thus give a false idea of the dentition 
which Professor Owen’s description does not clearly remove, otz.' that the molar pattern is a development 
of the premolar pattern, and that the premolar-molar dentition is homodont. 
