179 



cellodus, Nuthetes*, &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 (Urotrichus, fig. 20, b) and Opossum 

 (Philander murinus, ib. a), 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 

 " 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.f, fig. 20, e) the extent of the dental series, lower jaw, 

 is six-sixteenths of an inch ; in Plagiaulax Becklesii, 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-sixteenths ; 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 penicillata 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" J. 



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. 



* Owen, < Quarterly Journal of the Geological Society,' 1854, vol. x. p. 420. 



t ' Prefatory Notice 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. Wateehouse 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 but moderately de- 

 veloped." — Nat. History of the Mammalia, vol. i. (1845) p. 256. 



