258 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
Some Opossums, e. g. the murine and dorsigerous Philanders (fig. 20, c)*, have 
the mandible intermediate in size between that in Plagiaulax minor (a) and in Plagi- 
aulax BecMesii (f) ; it is both shorter and weaker than in the latter species. A natu- 
ralist and good observer (Dr. Carter Blake, F.G.S.) has expressed to me his surprise at 
witnessing, while in Central America, the disproportion of size between those mouse-like 
predaceous Marsupials, and the Lizards and Snakes on which they prey. 
Fig. 20. 
A 
Plagiaulax minor. 
UrotricTius talpoicles. 
DidelpTiis murina. 
The above figures of the mandible and mandibular teeth are of the natural size. 
I am not cognizant of any grounds afforded by zoology which forbid the supposition 
that a mammal of five inches in length, with the carnivorous type of dentition of Plagi- 
aulax, may have been able to capture and kill the diminutive Lizards ( Saurillus , Ma- 
cellodus, Nuthetesf , &c.) abundantly associated with Plagiaulax in the Purbeck shales. 
Comparative anatomy suggests that the modifications of the dentition of Plagiaulax 
minor , as compared with the similarly sized Shrew ( TJrotricJius , fig. 20, b) and Opossum 
(. Philander murinus, ib. c.), would give the Purbeck marsupial both the disposition and 
power to attack and prey upon animals of a larger size and higher organization than 
worms and insects. But the question of the carnivority of Plagiaulax , if weighed by 
* In B. dorsigera, from tip of incisors to condyles, 10 lines ; in B. murina 11 \ lines, 
t Owen, c Quarterly Journal of the Geological Society,’ 1854, vol. x. p. 420. 
