OF THE MARSUPIALIA. 319 
From this formula it will be seen, that the number of molars, sixteen in the upper 
and eighteen in the lower jaw, exceeds that of any other known existing Marsupial, and 
makes an approach to the dentition which characterizes some of the insectivorous 
Armadillos. The resemblance to Dasypus is further carried out in the small size of the 
molar teeth, their separation from each other by slight interspaces, and their implant- 
ation in sockets which are not formed by a well-developed alveolar ridge. The mo- 
lars, however, present a distinct tuberculate structure ; and both the true and false ones 
possess two separate fangs as in their Marsupial congeners: the crowns of these teeth 
are, however, less produced than in any other Marsupials ; for only the triturating tu- 
bercles appear above the gum. 
The false molars present the usual compressed triangular 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 Myrmecobians are insectivorous, and shelter themselves in the hollows of trees, 
frequenting most, it is said, those situations where the Port Jackson Willow abounds. In 
the structure and proportions of its hinder feet the Myrmecobius resembles the Dasyurine 
family ; and in the slightly developed canines, the smooth external surface of the skull, 
the breadth between the zygomata, and the absence of the interparietal ridges, as well 
as in the general external form and bushy tail, it offers an especial approximation to 
the genus Phascogale. 
Intermediate however between Myrmecobius and Phascogale would seem to be the sta- 
tion held by the interesting extinct genera above alluded to. In Phascolotherium the 
affinity is manifested in the simple form, small size, and straggling disposition of the 
incisors and canines: in the other genus, Thylacotherium, it is displayed in the size and 
number of its molares. 
This, one of the most ancient mammiferous genera hitherto discovered, presents 
ten molars on each side of the lower jaw, which resemble in structure and close ar- 
rangement those of Phascogale and Didelphis, while they are intermediate in their pro- 
portional size to the teeth of these genera and Myrmecobius. The exact condition of the 
incisors and canines of the Thylacotherium has not yet been displayed in the fossil jaws 
which have béen discovered. 
B. SaLraToria. 
Genus Perameles (Bandicoots). 
: 5—5 ed 3—3 | 4—4 
Incisors 33) canines ;— ; premolars eae molars ——: = 48. 
This dental formula characterizes a number of Marsupials commonly known in Au- 
stralia by the name of Bandicoots; the hind legs are longer and stronger than the 
fore, and exhibit in a well-marked manner the feeble and slender condition of the se- 
