1278 CLASS MAMMALIA. 



an inner cingulum, and the molars consist of three subequal cones 

 or cusps of a trenchant form, arranged longitudinally. There were 

 apparently either three or four molars in different individuals of a 

 single species. The fourth premolar was preceded by a milk-tooth 

 resembling the true molars. It was considered by Sir R. Owen 

 that the lower true molars of this genus corresponded to those of 

 the existing Thylacinus, in which there is a bilobed blade and a 

 talon. According, however, to Professor Osborn, this interpretation 

 is incorrect ; and that observer considers that the three cusps of the 



Fig. 1147.— Inner view of the left ramus of the mandible of Priacodon/erox ; from the Upper 

 Jurassic of North America. Three times natural size, c, Coronoid ; g, Mylohyoid groove ; s, 

 Symphysis. The anterior teeth are wanting. (After Marsh.) 



Triconodont type represent the three main cusps of the tooth of 

 Phascolotherium (fig. 1 1 4 1 ), and also correspond to the three lobes 

 of the blade of the tritubercular molar of the Amphitherium type 

 (fig. 1 145); and he accordingly terms these three cusps the para-, 

 proto-, and metaconid, and considers that the talon (hypoconid) is 

 unrepresented. 



Family Dasyurid^. — With this family we come to the considera- 

 tion of the existing Marsupials. The Dasyuridce. is an exclusively 

 Australian family, comprising the largest known members of the 

 suborder, and is divided into the subfamilies Dasyurince and 



Myrmecobiince. These are always I. -, C. ~ ; but the number of 



cheek-teeth varies, although there are never more than three pre- 

 molars. In the pes the hallux is usually either rudimental or 

 absent, but the other four digits are well developed and subequal. In 



the Dasyurince. the number of cheek-teeth does not exceed -, the 



upper true molars have triangular crowns, and those of the lower 

 molars are differentiated into an anterior blade and a posterior talon 

 (fig. 1 145), like the lower carnassial tooth of many of the placental 

 Carnivora of the present day. The mylohyoid groove may be 

 present both in this and the next subfamily. The Tasmanian 

 Wolf is the sole living representative of the genus Thylacinus, in 



