OF THE MESOZOIC MAMMALIA. 
205 
second and third molars are the largest ; behind these the teeth gradually decrease 
in size.^ 
The ramxis of Spalaeotherium is very long and shallow, with a single main 
curvature from the condyle to the symphysis. The most distinctive feature is the 
remarkable elevation of the condyle and its confluence with the angle ; in the latter 
respect this genus approaches Diconodon and Phascolotherhim, but the condyle is 
much more elevated than in either of these forms. The condyle is broad transversely, 
and from its inner face a somewhat fractured ridge, representing the angle, extends 
forwards and downwards to the dental foramen. The pterygoid fossa is thus very 
deep, but contracted vertically. The mylohyoid groove disappears beneath the fourth 
molar. Another marked feature of the ramus is its contraction beneath the last molar. 
The lower border extends forwards without bending upwards at the symphysis. 
PERALESTES. Plate VIII, flg. 8. 
This genus is represented by a portion of a right maxilla, seen on the outer face, 
containing the last premolar, six molars and the alveoli of an incisor, the canine and 
three premolars. The distinctive feature of the genus is the molar pattern, in which 
we find a complete opposition of internal and external cusps, a further development 
of the partial opposition observed in Perainus and Spalaeotherium. 
The portions of the maxilla which remain are entirely uncharacteristic. In the 
forward fragment we can distinguish a part of the premaxilla with the small alveolus 
of the lateral incisor ; behind this a large alveolus belongs probably to the canine. 
Then follow two pairs of sockets, in the second of which are traces of fangs ; here were 
probably inserted and pm}. Behind this is a fractured interval with space for 
two premolars of increasing size.^ A portion of the bony palate is preserved in the 
specimen (PI. II, fig. 3, Mes. Mamm.), which shows that this interval has not been 
greatly increased by fracture, so it seems possible that there were five premolars (see 
Peraspalax). We may, however, provisionally regard the last premolar as pm*. 
This tooth is much more elevated than mh- the crown is supported upon two widely 
set fangs, with a broad base contracting above the cingulum in a pointed and nearly 
vertical cone. Behind this are five molars, of nearly uniform pattern, followed by a 
sixth of smaller size and rather obscure pattern. The crowns increase in height from 
m* to m*, and then rapidly diminish. The marked feature of the crown is the lofty 
» There is again a considerable discrepancy between the drawings accompanying Professor Owen’s Me- 
moir, and those here given. So far as the writer's observations went the enlarged molars, (PI. I, figs. 32 B and 
34 B) are decidedly incorrect. By a comparison of figure 7 with those in PI. I, No. 38, both from the same 
specimen, the reader can observe the errors of the draughtsnjan in the latter. Figure 7, and the enlarged 
molars in the text, do, however, approximately conform with the partly broken molars represented in fig. 36, 
A 5 Mes. Mamm., and those in fig. 38. What is more important they corre.=pond with Profetsor Owen’s 
description (p. 24),' which shows that he himself clearly understood the characters of these teeth. 
’ These alveoli are mentioned in Professor Owen’s Memoir, p. 33, but not studied in detail. A very care- 
ful examination of the maxilla; brings them out clearly as figured. 
