MARSUPIATA. 101 



other external organs, these minute offspring attacli themselves to the teats of their mother, 

 and remain fixed there until they have aeqmred a degree of develo])ement analogous to that 

 in which other animals are born. The skin of the abdomen is almost always so disposed 

 around the mamm;c as to form a pouch, in which these imperfect young are [ireserved as in a 

 second uterus; and into which, long after they can walk, they retire for shelter on the appre- 

 hension of danger. Two peculiar bones attached to the pubis, and interposed between the 

 muscles of the abdomen, support the jiouch, [and prevent inconvenient pressure of the young, 

 when grown, upon the bowels.] These bones are also found in the male, and even in those 

 species in which the fold that forms the pouch is scarcely visible. 



The matrix of the animals of this order does not open Ijy a single orifice into the extremity 

 of the vagina, but communicates with this canal by two bent lateral tubes. The premature 

 birth of the young a))pears to depend on this singular organization. The scrotum of the male, 

 contrary to w hat obtains in other quadrupeds, hangs before the jjcnis, which at rest is directed 

 backwards. 



Another peculiarity of the Marstipiata is, that, notwithstanding a general resemblance of 

 the species to each other, so striking that they were all long included in one genus, they 

 differ so much in the teeth, the digestive organs, and the feet, tliat if we rigidly adhered to 

 these characters, it would be necessary to separate them into distinct orders. They carry us 

 by insensible gradations from the Carnaria to the Rodentia* , and there are even some animals 

 which have the pelvis furnished with similar bones ; but which, being destitute of incisors and 

 even of any sort of teeth, have been approximated to the Edentata, where, in fact, we shall 

 leave them, under the name of Monotremata. [The latter are now more properly included 

 as a second order of the same superior division of Mammalia which contains the Marsupiatu, 

 by the general consent of physiologists.] 



In brief, it may be stated that the Marstipiata form a distinct class, parallel to that of 

 ordinary quadrupeds, and divisible into similar orders ; so that, if we were to arrange 

 these two classes into even columns, the 0i)0ssums, Uasyures, and Bandicoots, would )je 

 opposed to the insectivorous Carnaria, such as the Tenrecs and jMoles ; the Phalangers 

 and Potoroos to the Urchins and Shrews ; while the Kangaroos, properly so called, could not 

 well be compared with any other genus ; but the Wombat should be ])laced opposite tlie 

 Rodentia. Lastly, if we were to consider the bones of the pouch only [commonly desig- 

 nated marsupnal bones], and regard as marsupial all animals which possess them, the 

 Platypuses and Echidnas might compose a group parallel to the Edentata. 



Linufcus ranged all the species which he knew under his genus DidelpMs, signifying doidjle 

 matrix. The pouch is indeed in some respects a second one. 



[The Marstipiata, together with the Monotremata, is now generally regarded as a distinct 

 subclass, Ooovivipara, equivalent to tlie rest of the IMammalia. Its members are lower in 

 their organization than any other mammiferous animals, approxnuating the oviparous type 

 (and particularly Reptiles), in sundry details of their organization. The hemispheres of the 

 brain, for instance, (which is much reduced in size,) are not united by a corpus callosum ; 

 and they are observed to be very defective in intelligence, as is indicated by their phy- 

 sioijiiomyt: the blood also is returned to the heart by two ])rincipal veins, as m Birds 

 and Reptiles ; and the sutures of the skull never become united. In short, they hold an 

 analo^'ous relation towards other Mammalia, to that which the Botrachia present to all 

 otlier Reptlk's. Their incisor teeth frequently exceed six in number, which is the maxi- 

 mum throughout the rest of the class, — another indication of their inferiority. 



The geographic range of the Marstipiata, with the exceiition of the Opossum group 

 peculiar to America, is at present almost confined to Australia and the neighbouring coun- 



* Only upon the supposition tliftt tiie [fimwiiii,' Icctii of llie R<jd,'!it\a I x'/p'/aOj. la aiTonlfd by tli-.-ir turning to liiic tlie sticii with which thaj 

 are modilicil ineisors, which is unirc tlitin iJoiibtful.— Kd. ure tniittcn, rtUlicr than the hand that j;uides it. 



t A corioas illustration cf this ijiferiority oa the part ol the M'ir 1 



