74 Royal Institution .- — 



difications of this dentition resemble those of the latter genus in tb 

 retention of the premolar, after the last true molar has come int 

 its place, and in the superior size of the first, as compared with th 

 second and third incisors. He then described in detail the socket, 

 of the incisors, and the form and conditions of the molar teeth, 

 which are highly characteristic of the marsupiality of this huge anc 

 most strange extinct quadruped. The cranial characters, which 

 were next described, equally elucidate this affinity. The peculiar 

 facial bones were then described in detail ; that portion in advance 

 of the orbits forming, as it were, a short pedunculate appendage to 

 the rest of the skull, increasing in a remarkable manner in both ver- 

 tical and lateral extent as it approaches the muzzle, but not offering 

 any evidence of having borne a nasal horn, as thought to be probable 

 by Mr. Macleay. The cavity of the nose is divided by a bony 

 septum, — a character which Prof. Owen has lately found to exist 

 also in a rare species of living Wombat — to a much greater extent 

 than in other known marsupials. Wholly concurring in Mr. Mac- 

 leay's conclusions as to the marsupial nature of the fossil in ques- 

 tion. Prof. Owen does not think that it exhibits evidences of a 

 generic distinction from Diprotodon. The Professor suggested, 

 however, that probably the lower jaw, when found, may show some 

 peculiarities of dentition and proportions similar to those on which 

 he has founded the genus Nototherium. 



ROYAL INSTITUTION OF GREAT BRITAIN. 



March 12, 1858.— The Duke of Northumberland, K.G., F.R.S., 

 President, in the Chair. 



On the Lowest (Rhizopod) Type of Animal Life, considered in its 

 relations to Physiology, Zoology, and Geology. By William 

 B. Carpenter, M.D., F.R.S. 



Among the unexpected revelations which the modern improved 

 microscope has made to the scientific investigator^ there is perhaps 

 none more fertile in interest than that which relates to the very 

 lowest type of animal existence ; from the study of which both the 

 Physiologist and the Zoologist may draw the most instructive lessons, 

 whilst the Geologist finds in it the key to the existence of various 

 stratified deposits of no mean importance both in extent and 

 thickness. 



Though the doctrines of Prof. Ehrenberg, as to the complexity of 

 organization possessed by the minutest forms of Animalcules, have 

 now been rejected by the concurrent voice of the most competent 

 observers, working with the best instruments, yet the wonders of 

 anirnalcular life are not in the least diminished by this repudiation 

 of them. Indeed, as great and small are merely relative terms, it 

 may be questioned whether the marvel of a complex structure com- 

 prised within tlie narrowest space we can conceive, is really so great 

 as that of finding those operations of life which we are accustomed 

 to see carried on by an elaborate apparatus, performed without any 



