PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
259 
magnitude as a measure of force,” is not fully or fairly tested by the exclusive example 
of the most diminutive species. 
In Plagiaulax Falconeri (Ow. *, fig. 20, e) the extent of the dental series, lower jaw, 
is six-sixteenths of an inch ; in Plagiaulax Becldesii , Fr. (fig. 20, f) it is ten-sixteenths of 
an inch. The entire length of the mandible in this species, inclusive of the incisor, in a 
straight line, is 1 inch two-sixteentlis ; the depth of the ramus at the back part of the 
large carnassial is five-sixteenths of an inch. 
In the Weasel ( Mustela vulgaris, Cuv., fig. 20, d) the extent of the dental series, lower 
jaw, is eight-sixteenths of an inch ; the depth of the ramus at the back part of the large 
carnassial is two-sixteenths of an inch. 
With the greater relative depth and consequent strength of the jaw of Plagiaulax a 
greater size and strength of both laniary and carnassial teeth are concomitant. The 
condyle, which is on the level of the dental series in the Weasel, is below that level in 
Plagiaulax. Every modification of the small marsupial by which it departs from the 
little blood-thirsty Placental is in the direction of greater carnivority. 
In Phascogale jgenicillata the extent of the dental series, lower jaw, is fourteen-six- 
teenths of an inch. It has four true molars in such lateral series, with relatively smaller 
laniaries and still smaller sectorial premolars than in Plagiaulax ; the mandibular con- 
dyle is raised a little above the dental line; the carnivorous adaptation of both jaw and 
teeth is less marked than in the Purbeck marsupial. But what is the testimony in re- 
gard to the habits of the existing pouched carnivore no bigger than a rat \ 
Gould, who would be the last to repeat testimony to which zoology and comparative 
anatomy ran counter, writes “ Phascogale penicillata , small as it is, comparatively, is 
charged with killing fowls and other birds” f. 
I can bear personal testimony, and that to my own loss, of the attack and slaughter 
of nearly full-grown Shanghai Pullets by Mus decumanus. Comparative anatomy lends 
more aid to the credibility of the predatorial powers of the carnivorous marsupial than 
of the equally small rodent ; but that both of them do attack and destroy animals more 
than twice their size and weight is a zoological fact. 
Though magnitude may be, in one sense, a measure of force, it by no means neces- 
sarily implies the application of such force, and consequently is any thing but “ an 
important ingredient ” in the question of the carnivority of Mus, Mustela , Phascogale, 
and Plagiaulax. 
But whatever bears on the interpretation of the singular dentition of the small “ pau- 
cidentate ” marsupial, logically applies to the larger one. 
Mr. Krefft gives drawings of sections of the “ lower incisor of Thylacoleo , Nototherium, 
Monograph of the Fossil Mammalia of the Mesozoic Formations, p. 84, plate iv. figs. 16, 16 a. 
t “ Mammals of Australia,” fol. Introduction, p. xviii. Mr. Waterhouse remarks, “ In the Phascogales, 
where the two foremost of the lower incisors are large, their increased development is, as it were, at the ex- 
pense of the posterior incisors, which are very small, and the canine which follows them is hut moderately de- 
veloped.”— Nat. History of the Mammalia, vol. i. (1845) p. 256. 
