12 



NA TV RE 



[May 5, i8c^: 



fact, since the occurrence of mammals allied to those of 

 the European Lower Eocene is quite capable of explana- 

 tion by their survival to a later period in South America. 



One of the new Patagonian forms, to which Dr. 

 Ameghino applies the name Prothylacwus, is stated to be 

 an animal of the general conformation of the Thylacine, 

 having apparently the same number of teeth, although 

 the upper incisors are unknown. The main distinction 

 of the fossil genus is, indeed, said to consist merely in the 

 circumstance that the lower premolars are more widely 

 separated from one another ; the molars of the two forms 

 being described as absolutely identical in character. The 

 fossil likewise exhibits the marsupial inflection of the 

 angle of the lower jaw. The absence of the upper in- 

 cisors in the specimens of Prothy /acinus is fortunately 

 compensated in another genus described under the un- 

 couth name of Protoprovh'erra. Here we find that the 

 number of teeth is exactly the same as in the Thylacine, 

 there being four upper and three lower incisors, a canine, 

 three premolars, and four molars on each side of the 

 skull. This dentition agrees numerically with that of the 

 Tasmanian Devil ; with the exception that there is an 

 additional premolar in each jaw. These fossils also 

 exhibit the inflection of the angle of the mandible, and 

 the presence of unossified vacuities in the palate, which 

 we have seen to be mai-supial features. 



As might have been expected to be the case, Dr. 

 Ameghino also states that there appears to be a complete 

 passage from these marsupial forms to others belong- 

 ing to that group of primitive carnivores known as Creo- 

 donts, of which the European Upper Eocene Hycsnfldo7i 

 and Pierodon are well-known examples. Now, if we are 

 to trust these descriptions (and there appears every reason 

 why we should), we must admit that Prothylacinus and 

 Protoproviverra are veritable marsupials of an Australian 

 type. Then comes the question. How are we to explain 

 the occurrence of such closely allied forms in areas so 

 remote from one another as Patagonia and Australia .^ 



It had long ago been urged that the occurrence of car- 

 nivorous marsupials in South America and Australia and 

 nowhere else (at the present time) indicated a former 

 connection between those two areas. To this, however, 

 Mr. Wallace ("Distribution of Animals," vol. i. p. 399) 

 objected that the American opossums {Didelphyida;) were 

 not an Australian type, and that they occurred in the 

 Tertiaries of Europe ; and hence he argued that both 

 the American and Australian marsupials probably took 

 their origin from the presumed marsupials of the European 

 Jurassic rocks. This explanation, on Mr. Wallace's own 

 showing, will not, however, hold good for the close re- 

 semblance stated to exist between the American Prothy- 

 lacinus and the Tasmanian Thylacine, since it is quite 

 impossible to believe that two such similar forms could 

 have maintained their likeness in such remote regions 

 after having diverged from a common European ancestor 

 as far back as the Jurassic period. 



It has, however, been long known that there are certain 

 very remarkable relationships between the fauna and 

 flora of all the great southern continents. For instance, 

 among mammals, the rodent family Octodontidce is 

 peculiar to South (including Central) America and 

 Ethiopian Africa. Then, again, among fishes, the family 

 of the CJiromidce is confined to the rivers of South 

 America and Africa, with one outlying genus in India ; 

 while the true mud-fishes {Lepidosiren and Protopterus) 

 are solely South American and Ethiopian, the third re- 

 presentative of the same family being the Baramunda 

 {Neoceratodus) of Queensland. Again, the connection 

 between the flora of Africa and that of Western Australia 

 is so intimate as to have induced Mr. Wallace {pp. cit., 

 p. 287) to express his belief that there must have been 

 some kind of land connection, although not necessarily a 

 continuous one, between these two widely distant areas. 



NO. I I 75, VOL. 46] 



The connection between the fauna of India and that of 

 Ethiopian Africa is now too well known to stand in need 

 of comment. The matter does not, however, end here ; 

 for if we go back to the Mesozoic epoch there are 

 equally striking evidences of the connection between the 

 faunas and florasof the southern continents. For instance, 

 the extinct saurian genus Mesosiernum, which appears to 

 have been allied to the Plesiosaurs of the Lias, is known 

 from early Secondary strata in Brazil and South Africa, 

 and nowhere else. Then, again, the remarkable Anomo- 

 dont reptiles {Dicynodon, &c.) of South Africa are 

 closely connected with those of India ; while the re- 

 spective alliances between the Labyrinthodont amphi- 

 bians and the Mesozoic floras of South Africa, India, 

 and Australia are too well known to need more than 

 mention. 



It appears, then, that, altogether apart from the new 

 I discovery, the common factors connecting the faunas and 

 floras of the four great southern prolongations of the con- 

 tinental land of the globe undoubtedly point, not only to 

 a more or less intimate connection between these several 

 areas, but also to their more or less partial isolation 

 from the more northern lands. 



Reverting to the new discovery, it may be observed 

 that our comparatively intimate acquaintance with the 

 Tertiary faunas of Europe and North America renders it 

 in the highest degree improbable that marsupials of an 

 Australian type lived during that time in either of those 

 areas. It is, however, quite possible that they rnay 

 turn up at any time in Tertiary formations in Africa, 

 while there is nothing to show that they may not also 

 have existed in peninsular India. Indeed, if we put 

 aside as improbable any connection by way of the Pacific 

 between South America and Australia, it seems impos- 

 sible to give any explanation of the occurrence of allied 

 marsupials in Patagonia and Australia without the 

 assumption that their ancestors existed in some part of 

 the great area lying between eastern South America and 

 Western Australia. R. Lvdekker. 



PHOTOGRAPHY IN COLOURS. 



THE Cotnptes rendus for February 2, 1891, contained 

 a brief note on colour photography, describing 

 the method employed by M. G. Lippmann, who had 

 been able to produce photographically the image of the 

 spectrum with all its colours. A summary of this 

 note was given in Nature at the time (see vol. xlviii., 



P 360)- 



M. G. Lippmann, who has been continuing his re- 

 searches, has communicated further results, which appear 

 in the Comptes rendus for April 25 (No. 17, vol. cxiv.). 

 These results show that we are not far off the solution of a 

 question which has been the aim of all the latest photo- 

 graphic researches. The following is a translation of the 

 note in question : — 



In the first communication which I had the honour to 

 make to the Academy on this subject, I stated that the 

 sensitive films that I then employed failed in sensitiveness 

 and isochromatism, and that these defects were the chief 

 obstacle to the general application of the method that I 

 had suggested. Since then I have succeeded in improving 

 the sensitive film, and,^althoughfmuch still remains to be 

 done, the new results are sufficiently encouraging to 

 permit me to place them before the Academy. 



On the albumen-bromide of silver films rendered ortho- 

 chromatic by azalin and cyanin, I have obtained very 

 brilliant photographs of .spectra. T> Alljthe colours appear 

 at once, even the red, without the interposition of coloured 

 screens, and after an exposure varying from five to thirty 

 seconds. 



