44 FOSSIL MAMMALIA OF THE 



seems to be smaller, but one cannot be sure that size may not be masked by matrix, 

 which I have thought it too hazardous to endeavour to clear away. The basal cusps are 

 best marked in the fourth and sixth teeth. 



At the fractured fore part of this jaw is the crown of a small tooth, which slopes 

 obliquely forward (as in i 3, fig. 11 a); it is probably an incisor. The socket of a larger 

 simple tooth follows, answering to the canine in fig. 11a. 



Peramus tenuirostris {minor?). Plate II, figs. 13, 13 a. 



The left ramus, wanting the ascending portion, of a long and slender mandible with 

 the inner side exposed (PI. II, figs. 13 and 13 a), I refer, from its shape and the character 

 of the few teeth it retains, to the same genus, if not species, as the two foregoing 

 specimens. 



The angle at which the pterygoid depression terminates anteriorly suggestively 

 resembles that of the outer depression in fig. 10 a, and ofiers the same distinction 

 compared with the inner surface of the mandible of Amblotherium, shown in PL II, 

 fig. 1 A, as has been pointed out in regard to that specimen. The mylohyoid groove 

 is wide at its hinder half and straighter in its course than in Amblotherium or 

 Achyrodon. 



The preserved fore part of the base of the coronoid, and a neatly defined impression 

 of the remainder, show a shallow emargination of the summit which may be due to 

 fracture, as is doubtless the deeper notch there in the mandible (fig. 10 a, c). But the 

 coincidence is noteworthy. If one could trust the part of the impression marked b, 

 in fig. 13 a, as showing the position of the condyle, it would seem to be relatively 

 higher, and divided by a shorter and more angular notch from the coronoid than in the 

 type of Peramus tenuirostris (fig. 10 a, b). The anterior part of the inward production 

 of the lower border of the depression on the inner side of the ascending ramus indicates 

 the marsupial character, but is not preserved backwardly far enough to show any down- 

 ward extension of an angular process, as at a in figure 10 a. 



The crowns of two molars are partially preserved, and the roots of two in advance are 

 visible. A chief cone, and indications of smaller basal cusps, as in m 4, fig. 10 a, are 

 plainly shown. 



The end of the symphysis has been broken and displaced slightly upward, so that 

 one cannot satisfactorily or with certainty conclude as to a difference, or the degree of 

 difference, from the shape of that part in fig. 11a. If the mandibular ramus (fig. 13, 

 PI. II) should exemplify more than a sexual inferiority of size of Peramus tenuirostris, it 

 might bear the specific name minor. I do not recognise grounds for generic distinction. 



