OF THE MESOZOIC MAMMALIA. 
22 !) 
curved sometimes bifanged. The incisors are compactly placed and recurved. There 
IS no diastema. The angle and condyle are upon the same level. 
PRIACODON, Marsh/ 1887. 
This formula is somewhat uncertain, as the 
Syn. Tinodon ferox, Marsh.^ 
Dentition~i cj, pnii, m^. 
type may be immature There is 
a diastema behind the canine, fol- 
lowed by three premolariform teeth. 
The fourth tooth is molariform but 
may represent a milk molar, in which 
case this genus is a synonym of Tri- 
conodon. The dentition, as given by n- , 
•W- X . - - X , ” ^ Figuke loa. Right lower jaw of Priacodon (Tnconodon) 
iViarsn, is pm^, m^, but may prove to ferox, inner view; three times natural size. After Marsh. 
be pmi, di = mp ’ The first molar lacks the full sized cusps which characterize Wi 
in tlie adult Th-iconodon, and resembles the milk molar of T. serrula, Owen. 
’ b. PHASCOLOTHKRJINM:' 
Lateral molar cusps upon inner slopes of central cusps. Extensive reduction of 
premolar series, or, premolars and molars alike. Angle confluent with lower border 
of mandible. 
PHASCOLOTHERIUM, Owen/ 1839. 
Dentition — ij, ci, pnio, m^. The incisors are styloid and separate. There is a 
wide diastema behind the canine. Premolariform teeth are wanting. The molars 
have a stout central cusp hearing the smaller anterior and posterior cusps somewhat 
upon its inner face. The angle is represented by the inflected lower border. 
TINODON, Marsh,' 1879. 
This genus is distinguished from Phascolotherkim by the presence of eight or 
more teeth behind the canine {fide Marsh), and 
by the inward rotation of the lateral cusps. So 
far as known at present it is closely similar in all 
other respects. 
c. SPA LA CO THERIINAE. 
Lateral cusps of lower molars strongly ro- 
tated inwards. Preniolars full or not greatly re- 
duced in number, and unlike molars. Angle and condyle confluent with lower 
border of mandible. 
Figure Right lower jaw of Tinodon 
bellus, inner view ; three times natural size. 
After Marsh. 
’ Loc. cit., p. 341. 
= “Am. Journ. Sc.,” 1880, p. 236.' 
’ Sub. fam. nova. 
* “ Geological Transactions,” second series, 'Vol. 6, p. 58. 
' “Am. Journ. Sc.,” 'Vol. 18, p. 216. 
