April 25, 1872] 



NATURE 



503 



by the heaping up of the water by the winds ; for any 

 amount of power which could possibly be derived from 

 such a source must fall enormously short of that required. 



It may be noticed that we have here a means of 

 making a somewhat rough estimate of the absolute 

 amount of resistance offered to oceanic circulation, a 

 rather obscure point. It shows that the resistance to 

 motions arising from friction is far greater than was 

 hitherto supposed. The amount of the work of the re- 

 sistance to a pound of water passing from the equator to 

 lat. 60° cannot be less than twice 9,025 foot-pounds. 



It follows also that if the resistance to motion in the 

 waters of the ocean be as great as it has thus been 

 proved to be, then there is no warrant for the generally 

 received opinion that a force such as that of the winds 

 acting on the surface of the ocean cannot produce motion 

 extending to any considerable depth. For if the resistance 

 to motion be as great as the foregoing consideration 

 shows it to be, it is impossible that the upper layers of the 

 ocean can be constantly pushed forward in one direction 

 without dragging the underlying layers after them. 



The inadequacies of the gravitation theory may be 

 shown in an even still more striking manner. Conceive 

 a column of water in any part of the ocean extending from 

 the surface to the bottom. Suppose the column to be a 

 foot square, and the depths of the ocean to be four miles. 

 We have in this case a column a foot in thickness, and 

 four miles in height measured from its base. According 

 to Dr. Carpenter's theory, gravity tends to move the water 

 forming the upper part of the column in the direction 

 from the equator to the pole, and the water forming the 

 under part from ti;e pole to the equator. What then is 

 the amount of force exerted by gravity on the entire 

 column? In the next part of my paper on Ocean Cur- 

 rents in the PIiilosiTphical Magazine I shall demonstrate 

 by an exceedingly simple and obvious method, that the 

 total amount of force exerted by gravity on the whole 

 mass of water constituting the column is only -f^^ of a 

 grain. That is, -^^ of a grain on 600 tons of water. 



Edinburgh, April 15 James Croll 



THE FOSSIL MAMMALS OF A USTRALIA 



THE substance of this communication was given 

 orally at the meeting of the Royal Society, April 

 18, 1872. 



Prof. Owen commenced by alluding to the series of 

 fossils brought in 1836 by the then Surveyor-General of 

 Austraha, Sir Thomas Mitchell, from the bone caves dis- 

 covered by him in Wellmgton Valley, New South Wales. 

 The determination of these remains required study of the 

 osteology and dentition of the existing marsupial animals, 

 which formed the subject of papers in the " Transactions 

 of the Zoological Society " (vol. ii., 1838, and vol. iii., 1845). 



In these papers indications were given of a second 

 species of living wombat, distinct from the type peculiar 

 to Tasmania, such indications being yielded by a skull 

 sent from Australia. In 1S53 the author published, in his 

 " Osteological Catalogue of the Museum of the College of 

 Surgeons," the cranial characters of a third living species 

 oi Phascolomys, also from a skull, which, like that of the 

 second species, was from the continent of Australia. 

 These materials seemed to some naturalists inadequate 

 for the acceptance of a Pliascoloinys latifrons and a Phas- 

 colomys platyrhiniis, in addition to the first discovered 

 Tasmanian Phascolomys vombatus; and Gould in the 

 part published in 1855 of his great work, " The Mammals 

 of Australia," containing the tine figure of that species, 

 hesitated to admit more, although a drawing which he had 

 received of the head of a wombat killed in South Australia 

 " afforded good reason for concluding that the continental 

 animal is really distinct." In 1859 this distinguished 



• "On the Fossil Mammals of Australia," No. y\\\.:0<imxiPhascolo7njis; 

 spegies exceeding the present in size, by Prof. Owen, F.R.S. 



naturalist was able to publish in Part XI. of his work a 

 figure of a wombat from the southern parts of the conti- 

 nent of Australia, which he recognised as distinct from the 

 small wombat of Tasmania, and referred to the Phasco- 

 lomys latifrons ; it was, however, the larger bare-nosed 

 species, Phascolomys platyrhiniis. 



In 1S65 and 1866 specimens were received at the 

 Zoological Gardens of London, of both the conti- 

 nental Australian wombats, which the able Prosec- 

 tor, Dr. Murie, showed to have respectively the 

 cranial characters of Phascolomys latifrons and Phase, 

 platyrhiniis. The /'//. latifrons had the nose or muzzle 

 clothed with hair. This confirmation greatly encouraged 

 the speaker in the investigation and comparison of the 

 cranial and dental characters of the fossil remains of the 

 genus ; and in November 1871, he felt that he had grounds 

 for submitting to the Royal Society such characters of 

 four other species of wombat, not exceeding in size the 

 largest of the existing kinds, which four species appeared 

 to have become extinct on the continent of Australia. 

 The differentiation of the actual platyrhine and latifront 

 species from some of the extinct forms was not the less 

 interesting and instructive ; though it seemed small in 

 degree, it was, however, definite, in comparison with other 

 fossil remains which could not be distinguished from the 

 existing Phascolomys platyrhiniis axiA Ph. latifrons. 



The determination of the species propounded on cranial 

 and dental characters in the present paper was much 

 easier and more decisive, by reason of the marked 

 superiority of size of the fossils. These large and gigan- 

 tic wombats were differentiated, not only by bulk, but by 

 modifications of the skull and proportions of certain teeth, 

 notably the incisors and premolars. 



On these grounds the author characterises a Phasco- 

 lomys mcdiiis, which, although markedly larger than 

 Phascolomys platyrhiniis, was intermediate in bulk be- 

 tween the two now known extremes of size in the genus. 

 Next followed a Phascolomys magnus,a.i\A finally a Phas- 

 colomys gigas. Of the latter species a restoration was 

 given in a diagram of the natural size, which was that of 

 a tapir or small ox. The dental and certain cranial 

 characters were illustrated by highly finished drawings of 

 the fossils. 



With respect to the large extinct wombats described 

 in his present paper, the author remarked that it was not 

 likely they could have escaped detection if still existing 

 in any of the explored parts of the Australian Continent. 

 The knowledge that such species have existed may excite 

 to research and help to their discovery, if any of them 

 should still be in life, in the vast tracts of the northern 

 and warmer latitudes of Australia. 



The author exhibited in a tabular view the localities of 

 the known existing and extinct Australian wombats as 

 follows : — 



Where found 



By whom found 



Species of 

 Phascolomys. 

 BrecciaCave, Wellington Valley.l Sir ThomasMitchcll,! ,,., , ... 



N. S. Wales 

 Lacustrine Bed, Victoria .. 

 Drift Deposits, Queensland 



c.B.,1836 r 



r E. C. Hobson, M.D.,1^. 



lb. King's Creek, Darling Downs S. Turner, 1847 ... Parvus, Medins 

 T2 n ■* // f Fred. Neville Isaac,)nr-j / 7/- 



Id. Eton Vale, 11' 



ib St. Jean Station, //'. 

 lb. Drayton, Queensland 



Ed. S. HLIL 



\Platyrkhitts, Med- 

 'ji'us, Magmts,Gisas 

 M. Satche St. Jean,\^. 



1864 ...1'^'^''^ 



Sir Danl. Cooper, B t. , 1 Thomso7ii, Medius 

 ) Mag-mis, Gigas 



■^/l.^r'!'^!.'!'' .^'"'!?." ^.'.''".!:} ^- Nicholson, ^K(,...]Giga: 

 Caves, Wellington Valley, N.S.i Professor Thomson,G.1i»///<:fc//z, ATrc^/;, 

 Wales J Krefft, 1867 / Lati/mis 



The author then touched upon some generalisations 

 suggested by the present stage of discovery. The dis- 

 appearance of the larger species was explicable on the 

 principle of the " contest of existence," as apphed by him 

 to %\vi problenx of the extinction of the fossil birds of 



