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 thi* second and third incisors. He then described in detail the sockett of the incisors, and the form and conditions of the molar teeth, which are highly characteristic of the marsupiality of this huge and 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 animalcular 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 the 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
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