224 



Dentition of Myrmecobius. 



TEETH OF DIPJIYODONTS. 237 



Marsupials approximates to the insectivorous type, and leads 

 thereto from the flesh-feeding genera. 



Myrmecdrius is characterised by the following remarkable 

 dental formula : — 



.4.4 1.1 3.3 6.6 



1 3.3 ;C 1.1 ^3-3^6.6 = 54 ' fig ' 224 - 



The number of true and false molars, eighteen in both jaws, 

 exceeds that of any other known existing Marsupial. The molars 

 are multicuspid, and both the 

 true and false ones possess 

 two separate fangs. The in*- 

 ferior molars are directed 

 obliquely inward, and the 

 whole dental series describes 

 a slight sigmoid curve, fig. 

 225. The premolars present 

 the usual compressed trian- 

 gular form, with the apex slightly recurved, and the base 

 more or less obscurely notched before and behind. The canines 

 are very little longer than the false molars. The incisors are 

 minute, slightly compressed, and pointed; they are separated 

 from each other and the canines by wide intervals. 



The extinct genus Amphitherium is founded on fossil remains 

 of lower jaws and teeth discovered in the oolitic slate at Stones- 

 field, in Oxfordshire, and it receives elucidation from the dental 

 characters of the previous genus, but is remarkable for 995 

 having a still greater number of molar teeth. The 

 dental formula is as follows : — 



. ?.? ?.? ?.? ?.? 



*373 ;c iTT ; ^ ;m 6^ 



There being thus thirty-two teeth in the lower jaw, 

 and probably as many in the upper jaw. 

 The following dental formula — 

 .5.5 1.1 3.3 4.4 



W C ?P 3^ m 4.4 = 48 ' 



characterises a number of Marsupials commonly known 

 in Australia by the name of Bandicoots, fig. 226. The 

 teeth which offer the greatest range of variation in the 

 present genus (Perameles) are the external or posterior Mandibular 

 incisors and the canines : the molars, also, which ori- comus. 

 ginally are quinque-cuspidate, have their points worn away, and 

 present a smooth and oblique grinding surface in some species 

 (fig. 222, m, vol. ii.) sooner than in others. 



