P. BECKLESII AND P. MINOR. 419 



perpendicular immediately behind it. The neck -portion of 

 the sigmoid notch (cl, e) is as long as the breadth of the 

 coronoid, so that the articular surface is not only depressed 

 below the apex of the coronoid, but projected a long way 

 behind it. A line drawn from the condyle to the gibbous 

 prominence on the wall of the last molar {%) considerably 

 exceeds the length of the horizontal ramus from the latter 

 point on to the border of the incisive alveolus. The inner 

 surface of the ascending ramus behind the orifice of the 

 dentary canal (n) is smooth, and near its inferior border 

 traversed by a longitudinal channel which bends back to the 

 under edge of the condyle. The orifice of the canal (n) is 

 low and directly in a vertical line with the posterior wall of 

 the last molar, being relatively situated exactly as in Hypsip- 

 rymnus. The anterior margin of the canal forms a raised 

 step, the edge of which is continued upward in a low crescentic 

 ridge to join on with the base of the gibbous prominence of 

 the last alveolus. The mylo-hyoid groove traverses the ridge 

 about the middle, but the adhesion of the inner surface of 

 the front piece (a, b) to the matrix does not at present admit 

 of its being determined how far the groove advances upon 

 the horizontal ramus. The inner surface of the coronoid is 

 convex, but this appearance is partly obscured by the plate 

 of the process being traversed by numerous fissures, with 

 partial displacement of the pieces. 



The inferior margin of the hind part of the ramus is nearly 

 horizontal ; it terminates suddenly in the lower edge of the 

 condyle. A narrow fractured surface (PL XXXIII. fig. 4, o), 

 the continuation of which was evidently directed inwards 

 {i.e. presented to the observer), is seen on the side of the 

 lower edge, stretching from the anterior boundary of the 

 dentary foramen (n) on to the condyle. The rest of this in- 

 flected margin (what remains of it) is seen embedded in the 

 opposite slab (PL XXXIII. fig. 1, b, o'). It forms a lamina 

 of great tenuity. The base of its inner bounding r'.dge shows 

 a triangular fracture immediately under the orifice of the 

 dental canal (at n, fig. 4, PL XXXIII.), where it is compara- 

 tively thick ; thence the section becomes gradually attenuated 

 on to the condyle. There can be little doubt that this is the 

 characteristic marsupial inflected angle, although feebly de- 

 veloped. It may have formed a slender elongated apophysis, 

 with little inward inflexion, as in Acrobata. 



The characters of the anterior portion of the inner side of 

 the horizontal ramus, which are concealed by the contact 

 with the matrix in the fragment PL XXXIII. fig. 1, a, b, are 

 beautifully shown by a detached piece lately received from 

 Mr. Beckles, represented by figs. 11-13. It comprises the 



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