OF THE MESOZOIC MAMMALIA. 
265 
lower dentition is from No. 47,775 in the British Museum collection ; che tij)S of the first and 
second premolars are restored from a specimen of T. occisor ; the canine is from a matrix 
impression, and the incisors from another specimen of T. ferox (Mes. Mamm., PI. IV., 
fig. 1). The angle and condyle are drawn from another specimen of T. ferox. The max- 
illary dentition, also viewed upon the inner surface, is from Nos, 47,788 and 47,779, which 
have the third premolar in common. 
Figure 5. Triaca7tthodon (Triconodon) serrula. The outer surface of the left mandibular 
ramus. Drawn from the original specimen. No. 47,763. Enlarged 31 diameters. 
Figure 6. Peramus tenuirosfris. The outer surface of the left mandibular ramus, enlarged 4J 
diameters. The main portion of the ramus with three molars and the last premolar is 
drawn from No. 47,742; the premolar crowns and symphysial portion of the ramus is 
from No. 47,744; these specimens have and w, in common. 
Figure 7. Spalacotherium triciispidens. The inner surface of the left mandibular ramus, re- 
versed. Enlarged 31 diameters. The ramus and dentition as far forwards as is from 
No. 47,750; the remainder of the figure is from the outer view of the forward portion 
of the same specimen in the counterpart block of matrix. The incisors are from other 
specimens. 
Figure 8. Peralestes longirostris. The outer surface of the right maxilla, enlarged 3i diame- 
ters. Drawn from a single specimen. ("Mes. Mamm., Plate II., fig. 3). 
Figure 9. Peraspalax talpoides. The inner surface of the left mandibular ramus, enlarged 31 
diameters. Drawn from a single specimen. No 47,738. The canine and anterior premo- 
lars are shown in the matrix impressions. 
Figure 10. Leptocladus dubius. The outer surface of the left mandibular ramus, enlarged 6 
diameters. Drawn from a single specimen. No. 47,739. 
Figure 11. Amblotherium soridnutn. The right mandibular ramus, seen upon the inner surface, 
and enlarged 51 diameters. This was drawn from a single specimen, No, 47,752. 
Figure 12. Phascolestes dubius. A portion of the left mandibular ramus, seen upon the inner 
surface, and enlarged 4 diameters. Drawn from a single specimen, No. 47,741. 
Figure 13. Achyrodon nanus. A portion of the right mandibular ramus, seen upon the inner 
surface, and enlarged 5 diameters. Drawn from a single specimen. No. 47,745. 
Figure 14. Stylacodon pusillus. The outer surface of the left mandibular ramus, enlarged 41 
diameters. The main portion is from No. 47,757. The coronoid and angle are from an- 
other specimen. (See Owen, Mes. Mamm., PI. II., fig. 15). 
Figure 15. Kuriodott pusillus. The inner surface of the left maxilla, enlarged 4 diameters. 
Drawn from a single specimen. No. 47,755. 15a represents the wearing surface of the 
molar crowns; e, the enamel encircling the crown; /, the enamel ridge traversing the 
crown; g, the external groove. 15b. represents the wearing surface of a left upper molar 
of Phascolomys urshms; letters e, e’ and g as above ; d, dentine between the median enamel 
ridge and the surface enamel. 
Figure 16. Bolodon crassidens. The outer surface of the right maxilla, enlarged 31 diameters. 
The anterior portion is from No. 47,735; the posterior portion is from another specimen. 
The specimens have four teeth behind the maxillo-premaxillary suture in common. 
16a wearing surface of the molar premolar-series. 
American Triassic. 
Figure 17. Dromotherium sylvestre. The inner surface of the left mandibular ramus, enlarged 
41 diameters. Drawn from a single specimen in the Museum of Williams College. 
