34 ] 
RECORDS OF W.A. MUSEUM. 
Specific Characters. 
Longitudinal links continuous with the outermost of the in- 
cumbent folds, low but distinct, a second link lower and very 
indistinct in a worn tooth ; present in the mid-valley of all the 
molars. Posterior basal ridge absent in Mi and but faintly seen in 
the other molars. 
Mandible thick, symphysis anchylosed. Incisor inclined, 
posterior dental foramen below the level of the teeth, level with the 
ectalveolar groove. Anterior edge of coronoid process rising at 
right angles to the line of the teeth. Under surface of the mandible 
arched upwards. Diastema short. Ramus thinner than in 5 . areas 
(De Vis) and deeper than in 5 . atlas (Owen). 
Differences and Resemblances. 
S. areas (De Vis)^ has the same general outline as our form, 
the same depth of ramus and an anchylosed symphysis. On the 
other hand its ramus is much stouter, 22. 5-25. 8mm. against 17mm., 
and the molars broader. 
S. atlas (Owen). This species, according to De Vis, is dis- 
tinguished from the preceding by having a much more slender 
ramus and by the fact that the symphysis is not anchylosed. In 
shape, too, the ramus is “flat exteriorly, increasing in depth pos- 
teriorly. Lower contour line flat or arched upwards.” Against 
this, our form is thick, the exterior surface is convex and the lower 
contour line arched upwards ; the symphysis is anchylosed. Again,, 
the incisor of the new species is much more erect and the diastema 
appreciably shorter. In the older form the depths of the jaw are 
26.1 to 28.5mm. and 29mm.-32.7mm., against 34 and 35mm. ; the 
teeth are smaller in the animal from the Eastern States. 
ADDITIONAL SPECIMENS. 
The collection contains numerous rami and portions of ramf 
belonging to members of this genus. 
They all belong to adult or aged (Thomas) animals, having; 
all the four molars in line and more or less worn. In consequence 
they give every opportunity for comparison with the type specimen 
1 De Vis, loc. cit, pp. 89 and 96. 
