MARSUPIALIA. 



257 



lection of experienced surgeons which have 

 been dispersed by some one or other of the 

 remedies in ordinary use, local or constitu- 

 tional; and how many that have resisted all 

 and remained stationary for years, the patient's 

 mind having been tranquillized by the assur- 

 ance of their innocency. Doubtltss on the 

 other hand a fatal result has sometimes ad- 

 ministered a silent but painfully intelligible 

 reproof to the over-confidence of the surgeon." 



( Samuel Sully.) 



MARSUPIALIA, (Marsupium, a pouch,) 

 Eng. Marsupials; Fr. Marsupiau.r ; Ger. Brit- 

 telthiere. 



Essential external character. Mammalian 

 quadrupeds, distinguished by a peculiar pouch 

 or duplicature of the abdominal integument, 

 which, in the males, is everted and contains the 

 testes ; in the females is inverted, covering the 

 mammae, and generally sheltering the young for 

 a certain period after their birth. 



Essential internal character. In both sexes 

 two supplementary trochlear bones are articu- 

 lated to the anterior part of the brim of the 

 pelvis, around which play the muscles em- 

 bracing and supporting the testes in the male, 

 and the mammary glands in the female ; these 

 bones, from their connexion with the pouch, 

 are called " marsupial." 



The quadrupeds associated together by the 

 common external and osteological characters 

 above denned, are ovo-viviparous or impla- 

 cental,* the vascular layer of the allantois not 

 being developed, so as to organize the villi of 

 the chorion, or to form cotyledons or a pla- 

 centa. The marsupial also differ from the 

 placental Mammalia in other important parts 

 of internal organization, as in the structure of 

 the brain and of the heart, and in the con- 

 dition of the sanguiferous and absorbent sys- 

 tems; and they present remarkable modifica- 

 tions of the genital apparatus in both sexes. 



Classification. The Marsupial animals are 

 generally of small size; some, as the Pigmy 

 Opossum (Petaurus pygnueus), and Dwarf 

 Phalanger ( Phalangista nana), are less than 

 the common mouse : the largest known existing 

 species is the common or Great Kangaroo 

 ( Macropus major). With the exception of 

 the Virginian Opossum, all the Marsupialia 

 are confined to the southern hemisphere of the 

 globe, and they are principally natives of Aus- 

 tralasia, to which part of the world several 

 remarkable genera are peculiar, and where, with 

 a few exceptions, as certain Cheiroptera and a 

 few Rodent genera, as Hydromys, Hapulotis, 

 and Psevdomys, all the known aboriginal 

 mammals are Marsupial or Monotrematous.f 



It is in the Australian continent that we per- 

 ceive the Marsupial quadrupeds typifying, so 

 to say, or playing corresponding parts With 

 those allotted to the placental Mammalia in a 

 larger theatre of the habitable surface of the 



* On the Generation of the Marsupialia, Philos. 

 Trans. 1834, p. 333. 



f The Dingo or Wild Dog is without doubt a 

 comparatively recent and accidental introduction, 

 VOL. III. 



earth. The carnivorous Thylacines* and Da- 

 syures,f for example, are the pigmy destruc- 

 tives of tlfe country, committing occasional 

 ravages among the sheep and poultry, but not 

 disdaining dead animal matter or garbage. 



The species of Phascogale, Myrmecobius, 

 and Perameles represent the placental Insec- 

 tivora. Many Marsupials which live in trees 

 have an omnivorous or vegetable diet ; these in 

 their prehensile tail and hinder thumb typify 

 the Quadrumana ; and one species, the tailless 

 Koala, seems to represent the American sloths 

 or the arboreal sun-bears of the Indian Archi- 

 pelago. 



Another species of Marsupial, the Wom- 

 bat, presents the dentition which characterizes 

 the placental Rodentia ; and the Petaurists, 

 like the Hying squirrels, have a parachute 

 formed by broad duplications of the skin ex- 

 tending laterally between the fore and hind legs. 



The Kangaroos are the true herbivorous 

 Marsupialia, and many interesting physiolo- 

 gical conditions present themselves to the mind 

 in contemplating the singular construction and 

 proportions of these animals. It would ap- 

 pear that the peculiarities of their gestation 

 rendered indispensably necessary the posses- 

 sion of a certain prehensile faculty of the 

 anterior extremities, with a free movement of 

 the digits and a rotatory power of the fore-arm, 

 in relation to the manipulations of the pouch 

 and of the embryo therein protected and ma- 

 tured. At the same time an herbivorous quad- 

 ruped must possess great powers of locomo- 

 tion in oider to pass from pasture to pasture, 

 and to avoid its enemies by flight. These 

 powers, as is well known, are secured to the 

 herbivorous species of the placental Mammalia 

 by an ungulate structure of four pretty equally 

 developed members. Such a structure, how- 

 ever, would have been incompatible with the 

 procreative economy of the Kangaroo. It is, 

 therefore, organized for a rapid course by an 

 excessive development of the hinder extre- 

 mities, and these alone serve the animal in 

 flight, which is performed by a succession of 

 extensive bounds. The tail, also, is of great 

 power and length, and, in the stationary po- 

 sition, the body is supported erect on the tripod 

 formed by the tail and hind legs, while in easy 

 progression the tail serves as a crutch, upon 

 which and the fore feet the body is sustained 

 while the hind legs are swung forwards. 



As the Australian Continent, the great me- 

 tropolis of the Marsupial quadrupeds, still 

 remains but very partially explored, and as 

 new species and even genera of Marsupials 

 continue at each expedition to reward the re- 

 searches of the scientific traveller; and as, more- 

 over, the recovery of two lost but distinct 

 genera from the ruins of a former world makes 

 it reasonable to suppose that other types of 

 Marsupials remain still hidden in the crust of 

 the earth, it can hardly be expected that the 

 zoologist should be able to arrange in a natural 

 series, with easy transitions according to the 



* The Hysena of the Colonists. 

 f The Devil, Native Cat, &c. of tlie Colo ists. 



S 



