TRANSACTIONS OP THE SECTIONS. 105 



On Marsupiata. By Professor Owen, F.R.S., S)-c. 



Mr. Owen briefly stated the results he had come to in the course of 

 his investigation of these animals, under the three following heads: 

 first, the zoology of Marsupiata ; secondly, their relation to other 

 Mammalia ; and, thirdly, the peculiarities of their reproductive econo- 

 my. 1. With regard to their zoological characters, they present as 

 many forms, and as varied habits, as all the Carnivora put together. 

 In their kind of food they are very various. Some are entirely car- 

 nivorous, as those of New Holland. Some are insectivorous, like the 

 Orycteropus and Myrmecophaga, among the other Mammalia. A spe- 

 cies of these is described by Captain King, as having a divided hoof like 

 the Ruminantia. Some of them are arboreous, as the Didelphes and 

 Perameles. Many of the Marsupiata are strictly herbivorous, as the 

 kangaroo-rat, &c. Mr. Owen thought, however, with all the varieties 

 of character and habit presented by these animals that they had been 

 too largely subdivided by zoologists. 2. In regard to their relation to 

 other animals, he was of opinion, that they ought to be considered 

 as one group; for although they differed greatly in some respects, 

 still they agreed in so many remarkable points, that they could not be 

 consistently separated. Of these points the most remarkable were the 

 development of the hind legs ; the existence of the marsupial bag ; the 

 circulatory apparatus being less perfect than in the rest of Mammalia, 

 the blood being returned to the heart by two veins, as in the hearts of 

 reptiles and birds ; and in the hemispheres of the brain, which are not 

 united by a corpus callosum. In this last respect, they are like the 

 oviparous division of vertebrate animals, a fact first pointed out by 

 Mr. Owen ; having the same relation to Mammalia, that the Batrachians 

 have to the Ophidian, Saurian, and Chelonian divisions of reptiles. 3. 

 The reproductive economy of these animals was slightly touched upon. 

 It had been supposed, that the young were produced by budding from 

 the marsupial pouch ; but this was now proved to be erroneous, and the 

 first stages of their uterine growth were known to be like that of other 

 Mammalia. 



Mr. Owen then entered into some geological account of these animals. 

 Dr. Buckland had found the jaw of an animal in the Stonesfield strata, 

 which, from a peculiar mark only seen in the jaw of Marsupiata, could 

 be Avell identified, and proved to be analogous to the present genus 

 Opossum, or Didelphis. Major Mitchell has in his collection a large 

 number of bones belonging to extinct genera of Marsupiata. From the 

 jaw of one of these animals, there is reason to conclude, that its pos- 

 sessor must have been double the size of any species of kangaroo ex- 

 isting at the present time. 



On PoucJied Rats. By J. Richardson, M.D., F.B.S., S}C. 



Dr. Richardson exhibited four very distinct species of American 

 pouched rats, or gophers, belonging to the genus Geomys. 



