258 



MARSUPIALIA. 



order of their affinities, the few and diversified 

 forms of this implacental group which are at 

 present known. 



In the subjoined classification the modifica- 

 tions of the digestive system have been taken as 

 the guide to the formation of the primary groups 

 of the Marsupialia. 



The Continent, however, in which the Mar- 

 supials exist in greatest number and variety, 

 is characterized by the paucity of organized 

 matter upon its surface, and consequently few 

 of the species are nourished by a well-defined 

 diet. No large carnivorous quadruped could 

 without much difficulty have found subsistence 

 in the wilds of Australia, prior to the intro- 

 duction of civilised 7nan and his attendant 

 herds; and we find, in fact, that the native 

 genera which are the most decidedly carnivo- 

 rous do not include species larger than the dog. 

 We can only reckon among these strictly car- 

 nivorous species the Thylacines and the Da- 

 syures ; and, on the other hand, not more than 

 two or three Marsupial genera feed exclusively 

 on vegetable substances. The remainder de- 

 rive a promiscuous nutriment from dead or 

 decaying animal and vegetable matter, crus- 

 tacea, and the refuse of the sea-shore, insects 

 in their perfect and larva states, live birds, 

 young and succulent sprouts, leaves, fruits, 

 &c. The terms, therefore, which will be given 

 to the different primary subdivisions in the 

 present classification of the Marsupialia must 

 not be understood to indicate strictly or ex- 

 clusively the nature of the food of the species 

 severally included in these groups, but rather 

 their general tendency to select for their support 

 the substances implied by those designations. 



Classification of the Marsupialia.* 



Tribe I. SARCOPHAGI. 

 The genera in this tribe are characterized by 

 an important anatomical condition, viz. the ab- 

 sence of an intestinum caecum. 



Genus 1. THYLACINUS. ( Fig. 80.) 



Fig. 80. 



Incisors 



33 

 33; 



Thylacinus Harrisii, one-third natural sixe. 

 44 11 



canines 



33' 



44. 



molars - = 46. 

 4 4 



11 



premolars 



Proceedings of the Zoological Society, Jan. 8, 



The incisors are of equal length and regu- 

 larly arranged in the segment of a circle with 

 an interspace in the middle of the series of 

 both jaws. The external incisor on each side 

 is the strongest. The laniaiy or canine teeth 

 are long, strong, curved, and pointed, like 

 those of the dog tribe. The spurious molars 

 in this as in all other Marsupials have two 

 roots ; their crown presents a simple com- 

 pressed conical form, with a posterior tubercle 

 which is most developed on the hindmost. 

 The true molars in the upper jaw are unequally 

 triangular, the last being much smaller than the 

 rest; the exterior part of the crown is raised 

 into one large pointed middle cusp and two 

 lateral smaller cusps obscurely developed ; a 

 small strong obtuse cusp projects from the 

 inner side of the crown. The molars of the 

 lower jaw are compressed, tricuspidate, the 

 middle cusp being the longest, especially in 

 the two last molars, which resemble closely the 

 sectorial teeth (dents carnassicrs) of the dog 

 and cat. 



The fore feet are 5-digitate, the hind feet 

 4-digitate. On the fore foot the middle digit 

 is the longest, the internal one or pollex the 

 shortest; but the difference is slight. On the 

 hind foot the two middle toes are of nearly 

 equal length and longer than the two lateral 

 toes, which are equal. All the toes are armed 

 with strong, blunt, and almost straight claws. 



The only known species of this senus, the 

 Thylacine (Thylacinus Harrisii, Temm., Di- 

 delphys Cynocephalus, Harris,) is a native of 

 Van Dieman's Land, and is called by the 

 Colonists the " Hyaena." It is the largest of 

 the carnivorous Marsupials, equalling in size 

 the shepherd's dog, but is of a broader build, 

 and stands lower on its legs. Its head is of 

 disproportionate magnitude. The principal 

 characteristic of its colour is the transverse 

 black bands which traverse the back. It dwells 

 in caverns and holes in the rocks, and seeks its 

 prey by night, devouring the smaller native 

 quadrupeds, and at the present day 

 committing destructive ravages on 

 the numerous flocks of sheep which 

 have been introduced by the Euro- 

 pean settlers into the island. Even 

 the spines of the Echidna seem to 

 be no defence against the destruc- 

 tive and voracious propensities of 

 the powerful Thylacine, for the partly 

 digested remains of one of these 

 monotremes have been found in its 

 stomach. 



In confinement the Thylacine 

 utters from time to time a short 

 guttural cry, and appears in the day- 

 time exceedingly inactive and stu- 

 pid, presenting an almost continual 

 movement of the nictitating mem- 

 brane of the eye. 



1839. The series of skulls carefully prepared by 

 Mr. Waterhouse at the Zoological Society have 

 afforded me the chief materials for the illustrations 

 of the dental formula: of the different Marsupial 

 genera. 



