NOVEMBKR 7, 1890.] 



SCIENCE. 



255 



fined to these two regions. Aphritis, a fresh- water genus, 

 has one species in Tasmania, and two in Patagonia. Another 

 small group of fishes known as the Haplochitonidm inhabit 

 Tierra del Fuegia, the Falklands, and South Australia, and 

 are not found elsewhere; while the genus Galaxias is con- 

 fined to south temperate America, New Zealand, and Aus- 

 tralia. Yet the lands which have these plants and animals 

 in common are so widely separated from each other that 

 they could not now possibly interchange their inhabitants. 

 Certainly towards the equator they approach each other 

 rather more ; but even this fact fails to account for the present 

 distribution, for, as Wallace has pointed out, '"the heat-lov- 

 ing Reptilia afford hardly any indications of close afBnity 

 between the two regions" of South America and Australia, 

 " while the cold-enduring A?rip/w'6ia and fresh-water fishes 

 offer them in abundance " (Wallace, Dist. of Animals. 14001. 

 Thus we see that to the north interchange is prohibited by 

 tropical heat, while it is barred to the south by a nearly 

 shoreless circumpolar sea. Yet there must have been some 

 means of intercommunication in the past, and it appears cer- 

 tain that it took the shape of a common fatherland for the 

 various common forms from which they spread to the north 

 ern hemisphere. As this fatherland must have been accessi- 

 ble from all these scattered southern lands, its size and its 

 disposition must have been such as would serve the emigrants 

 either as a bridge or as a series of stepping-stones. It must 

 have been either a continent or an archipelago. 



But a further and a peculiar interest attaches to this lost 

 continent. Those who have any acquaintance with geology 

 know that the placental Mammalia — that is, animals which 

 are classed with such higher forms of life as apes, cats, dogs, 

 bears, horses, and oxen — appear very abruptly with the in- 

 coming of the tertiary period. Now, judging by analogy, it 

 is not likely that these creatures can have been developed 

 out of mesozoic forms with any thing like the suddenness of 

 their apparent entrance upon the scene. For such changes 

 they must have acquired a long time, and an extensive 

 region of the earth : aud it is probable that each of them had 

 a lengthy series of progenitors, which ultimately linked it 

 back to loner forms. 



Why, then, it is constantly asked, if this was the sequence 

 of creation, do thf se missing links never turn up ? In reply 

 to this query, it was suggested by Huxley that they may 

 have been developed in some lost continent, the boundaries 

 of which were gradually shifted by the slow elevation of the 

 sea-margin on one side and its simultaneous slow depression 

 upon the other; so that tliere has always been in existence a 

 large dry area with its live-stock. Tliis dry spot, with its 

 fauna and flora, like a great raft or Noah's Ark, moved with 

 great slowness in whatever direction the great earth undula- 

 tion travelled. But today this area, witli its fossil evi- 

 dences, is a sea-bottom; and Huxley supposes that the con- 

 tinent, which once occupied a part of tlie Pacific Ocean, is 

 now represen'ed by Asia. 



This movement of laud-turface translation eastwards even- 

 tually created a connection between this land and Africa 

 and Europe; and if, when this happened, the Mammalia 

 spread rapidly over these countries, this circumstance would 

 account for the abruptness of their appearance there. 



Now, Mr. Blandford, the president of the Geological Soci- 

 ety of London, in his annual address recently delivered, 



advances matters a stage further; for he tells us that a grow- 

 ing acquaintance with the biology of the world leads natu- 

 ralists t') a belief that the placental Mammalia, and other of 

 the higher forms of terrestrial life, originated during the 

 mesozoic period — still further to the southwards, that is to 

 say — in the lost Antarctic continent, for the traces of which 

 we desire to seek. 



But it almost necessarily follows, (hat, wherever the Mam- 

 maliawere developed, there also man had his birthplace ; and, 

 if these speculations should prove to have been well founded, 

 we may have to shift the location of the Garden of Eden 

 from the northern to the southern hemisphere. 



I need hardly suggest to you that possibilities such as these 

 must add greatly to our interest in the recovery of any traces, 

 of this mysterious region. This land appears to have sunk 

 beneath the seas after the close of the mesozoic. Now, ther 

 submergence of any mass of land will disturb the climatic 

 equilibrium of that region, and the disappearance of an. 

 Antarctic continent would prove extremely potential in 

 varying the climate of this hemisphere; for to-day the sun's 

 rays fall on the south-polar regions to small purpose. The 

 unstable sea absorbs the heat, and in wide and comparatively 

 warm streams it carries off the caloric to the northern hem- 

 isphere, to raise its temperature at the expense of ours. But 

 when extensive land received those same heat-rays, its rigid 

 surfaces, so to speak, tethered their caloric in this hemisphere; 

 and thus, when there was no mobile current to steal north- 

 wards with it, warmth could accumulate, and modify the 

 climate. 



Under the influences of such changes, the icy mantle 

 would be slowly rolled back towards the south pole, and 

 thus many plants and animals were able to live and multiply 

 in latitudes that to-day are barren. What has undoubtedly 

 occurred in the extreme north is equally possible in the ex- 

 treme south. But if it did occur, — if south-polar lands, now 

 ice-bound, were then as prolific of life as Disco and Spitz- 

 bergeu once were, — then, like Spitzbergen and Disco, the 

 unsubmerged remnants of this continent may still retain 

 organic evidences of the fact in the shape of fossil-bearing 

 beds, and the discovery of such deposits would confirm or 

 confute such speculations as these. The key to the geologi- 

 cal problem lies within the Antarctic Circle, and to find it 

 would be to recover some of the past history of the southern 

 hemisphere. There is no reason to despair of discovering 

 such evidence, as Dr. M'Cormack, in his account of Ross's 

 voyage, records that portions of Victoria Land wei-e free 

 from snow, and therefore available for investigation, besides 

 which their surface may still support some living forms, for 

 they cannot be colder or bleaker than the peaks which rise 

 out of the continental ice of North Greenland; aud these, 

 long held to be sterile, have recently disclosed the existence 

 upon them of a rich though humble fiora. 



We have now to consider some important meteorological 

 questions. If we look at the distribution of the atmosphere 

 around the globe, we shall see that it is spread unequally. 

 It forms a stratum which is deeper within the tropics than 

 about the poles, and over the northern than over the southern 

 hemisphere, so that the barometer normals fall more as we 

 approach the Antarctic than they do when we near the 

 Arctic. Maury, taking the known isobars as his guide, has 

 calculated that the mean pressure at the north pole is 29.], 



