650 



HERBIVOROUS MARSUPIALS 



group of an insectivorous aud very probably marsupial family. The 

 character of the calvarium of Triconodon offers nothing adverse to the 

 above views."* 



Besides the mammalia above alluded to, belonging to 9 or 10 species 

 and to 5 or 6 genera, all of them insectivorous or predaceous, we are 

 indebted to Mr. Beetles for having disentombed (January 31, 1857,) the 

 remains of another genus exceedingly unlike the rest, the relations of 



I _'. i. 



• \ 



Plagiaulax Becklesii, Falc. 

 These two figures represent the same right ramus of the lower jaw seen on the opposite sur- 

 faces of a split stone, the two taken together affording data for a complete restoration of the jaw. 



Upper figure (outer side), 

 a, b, e'. Right ramus of lower jaw magnified two diameters, a, b, outer side, b, o', d', e\ im- 

 pression of inner side. 

 a. Incisor. 



6, c. Line of vertical fracture behind the pre- molars. 

 d'. Impression of the condyle in the matrix. 

 e'. Impression of top of coronoid process. 



/ Section of the anterior piece of the jaw at the fracture b, c, — a", inner surface ; y, outer. 

 The notch at the top is formed by one of the sockets of the double-fanged true molar. 

 g. Section of the hinder piece near b, c ; or, inner; y, outer surface. 

 o'. Broken off inflected fold of inner margin buried in the matrix. 

 in. Sockets of two molars. 

 p, m. Three pre-molars, the third and last divided by a crack. 



Lower figure (inner side), 

 a', d. Same lower jaw on the opposite slab of stone; 6, d, e, inner side; b, a', h, cast and im- 

 4 pression of outer side. 



Of. Outline of the incisor restored. 

 i, c. Line of vertical fracture. 

 tl. Condyle. 

 e. Coronoid. 



h. Impression on the matrix of the three pre-molars. 

 i. Empty sockets of the two true molars. 

 71. Orifice of dentary canal. 



o. Indication of the raised and inflected fold of the posterior inner margin. 

 k. Third or largest pre-molar, magnified 5* diameters, showing the 7 diagonal grooves. 

 /. Corresponding pre-molar in the recent Australian Hypsiprymnus Gaimardi, showing the 

 7 vertical grooves, magnified 3J diameters. 



e Allusion is here made to the crown of the skull before mentioned as occur- 

 ring in the same slab. In the text, at p. 295, I have cited the opinion given 

 by Professor Owen in 1854 (see Geol. Quart. Journ., vol. x. p. 431), that the 

 Spalacotherium was " more nearly allied to the placental than to the marsupial 

 insectivora, ' ' an opinion which, as will be 6een, he is now disposed to modify. 



