346 MARSUPIAL QUADRUPEDS OF NEW HOLLAND. 



finition of this class, as mammals, or animals provided with 



me great satisfaction to find that my views regarding the value and posi- 

 tion of the group, Monotremata, so entirely coincide with those of so dis- 

 tinguished a naturalist. They are contained in a letter dated Lund, in 

 Sweden, Aug. 3rd, 1833 ; and are a translation from a work recently pub- 

 lished by Professor Agardh, in the Swedish language, under the name of 

 *Allman Wext Biologi.' 



" The marsupials," says the Professor, " are Mammalia which approach 

 very nearly to birds ; the Monotremata in particular almost coincide with 

 them. Not only do the developed form of the hind legs, the deranged func- 

 tions of the anterior extremities, the position of the body, and the destination 

 of the tail to govern the pace, all indicate this affinity, but their internal struc- 

 ture is likewise very similar. They constitute a distinct group of Mamma- 

 lia, combining carnivorous as well as herbivorous animals, in the same 

 manner as birds contain predacious as well as frugivorous tribes. They 

 have no distinct internal uterus, for it is only the connection of the two ovi- 

 ducts to which that name has hitherto been given ; neither have they a pe- 

 culiar vagina, for the organ which Daubenton and GeofFroy thus distin- 

 guish, when they assert that the marsupials have two vagina, belongs rather, 

 according to the researches of Tyson, to the oviducts or Fallopian tubes : 

 so that, except in the doubleness of the parts, the marsupials resemble birds 

 in their organs of generation, as well as in other respects. The embryo 

 also is brought forth, not as in other Mammalia, perfectly formed ; but it 

 is produced in the state of an egg, and in that form deposited in the mar- 

 supium or uterus. Now the egg or embryo of the Mammalia has the pro- 

 perty of attaching itself to every part of the uterus at the point where the 

 placenta is formed ; and thus the embryo or egg of the marsupials fastens 

 itself to the mamma, and there communicates with the arteria epigastrica in 

 the same manner as in other Mammalia it communicates with the arteria 

 uterina. It is fastened by a cord resembling the navel-string, (though it is 

 unknown where this cord passes out from the embryo), which is often so 

 long that the embryo hangs out of the bag, and which at the moment of 

 real birth is separated by a rupture, as in the case of the placenta and ordi- 

 nary uterus. This external uterus, however, does not invariably assume the 

 form of a purse or bag ; in some instances it consists of simple folds of the 

 skin, and in the monotremes, even these disappear. 



" The monotremes bear a very strong affinity to the ordinary marsupials, 

 they likewise very closely resemble birds, not alone in the. construction of 

 the bill, cranium, clavicles, shoulder-bones, sternum, and undeveloped teats, 

 but especially in their organs of generation. These animals have only one 

 ovarium developed, as in birds, and both the Echidna and the Ornithorhyn- 

 chus lay eggs and hatch them. Thus it is that the uterus of the Mammalia 

 becomes modified in the marsupials, so as to be situated without the body, 

 and finally vanishes altogether in the Monotremata. 



" If we apply these considerations to ascertain the concatenation of the 

 various groups of animals, in relation to their organs of generation, we find 

 that it indicates one class, the Mammalia, which have an internal hatching 

 organ, called the uterus ; another class, the marsupials and monotremes, 

 in which this hatching organ is placed without the body, vanishing totally 

 in the latter group, the animals of which lay eggs and hatch them ; and 

 finally, a third class, birds, in which this property, which is irregular and 

 limited in the monotremes, becomes fully normal." — Allman Wext Biologi 

 afC. A. Agardh, p. 453. 



