POPULAR MISCELLANY. 



139 



period," and other turtlebacks not so ex- 

 plainable, " and seeming to betoken a period 

 of unknown direction before the working of 

 the quarries." In Durham Cave, Strouds- 

 burg, Pa., instead of a pre-Indian cave man, 

 a red man was found, " as the contemporary, 

 it seemed, of the peccary and giant chin- 

 chilla." In the chalk gorges of southern 

 Texas, apparently promising indications gave 

 only tokens of modern surface loam, which 

 had fallen and mingled with ancient under- 

 placed chalk. The cave at Lookout Moun- 

 tain was explored to the bottom. Teeth of 

 the tapir close to the layer of occupancy by 

 man, added, however, a new species to the 

 list of extinct North American mammals 

 thus far observed in like association with 

 human remains. The Nicajack Cave, in Ma- 

 rion County, Tenn., likewise failed to yield 

 any earlier than neolithic remains. 



Kinds of Ivory. Four principal kinds of 

 ivory are known in the market : that of Guin- 

 ea, the Gaboon, or Angola, which is a little 

 greenish, so that it is sometimes called green 

 ivory, and which whitens with age ; Cape 

 ivory, which is of a dull, light, somewhat 

 yellowish color ; Indian or Siamese ivory, 

 very rare, and white, with a tinge of rose 

 color ; and the fossil ivory of Siberia, re- 

 mains of the mammoths of the olden time. 

 Of these, the West African ivory is most 

 highly prized, being finer and more trans- 

 parent than the others. It is pretended that 

 experts, w'hen they see a well-preserved 

 tusk, can tell whether the animal that wore 

 it came from East or West Africa, or north 

 or south of the equator. The farther north 

 the animal's habitat, and the more elevated 

 and dry the situation, the more the ivory is 

 coarse and inferior. The principal market 

 for ivory is at Liverpool, and nearly one 

 third of the stock imported there is used in 

 the Sheffield cutleries. Another considerable 

 market is at Antwerp. The annual exports 

 of ivory from Africa represent the product 

 of sixty thousand elephants, and this means 

 a rapid reduction of the elephantine popu- 

 lation of the continent. Various artificial 

 ivories, or imitations, are manufactui-ed to 

 supply the increasing demand. There are 

 vegetable ivory tagua seed from Peru, or 

 wood injected with chloride of lime ; sheep 

 bone, macerated with the wastes of white 



skins; paper pulp with gelatin, celluloid, 

 and caoutchouc ; a preparation of potatoes ; 

 and a substance obtained by treating milk 

 with certain reagents. The expediency has 

 been suggested of establishing elephant 

 farms, to form a more certain source of sup- 

 ply than hunting wild elephants is destined 

 to become. Ostrich farming has proved prac- 

 ticable ; why not elephant farming too ? 



Migration of Birds. On the solution of 

 the problem of the migration of birds. Canon 

 Tristram said in the British Association, 

 much less aid has been contributed by the 

 observations of field naturalists than might 

 reasonably have been expected. The ob- 

 servable facts may be classified as to their 

 bearing on the whither, when, and how of 

 migration, and after this we may possibly 

 arrive at a true answer to the Why ? Ob- 

 servation has sufficiently answered the first 

 question. Whither ? There are scarcely any 

 feathered denizens of earth or sea to the 

 summer and winter ranges of which we can 

 not now point. Of almost all the birds of 

 the holo-arctic fauna we have ascertained 

 the breeding places and the winter resorts. 

 Now that the knot and the sanderling have 

 been successfully pursued even to Griunell 

 Land, there remains but the curlew sand- 

 piper of all the known European birds whose 

 breeding ground is a virgin soil, to be trod- 

 den, let us hope, in a successful exploration 

 by Nansen, on one side or other of the north 

 pole. Equally clearly ascertained are the 

 winter quarters of all the migrants. The 

 most casual observer can not fail to notice 

 in any part of Africa, north or south, west 

 coast or interior, the myriads of familiar 

 species which winter there. We have ar- 

 rived at a fair knowledge of the When ? of 

 migration. Of the How ? we have ascer- 

 tained a little, but very little. The lines of 

 migration vary widely in different species 

 and in different longitudes. All courses of 

 rivers of importance form minor routes. 

 Consideration of all lines of migration might 

 serve to explain the fact of North American 

 stragglers, the waifs and strays which have 

 fallen in with great flights of the regular 

 migrants, and been more frequently shot on 

 the east coast of England and Scotland than 

 on the west coast or in Ireland. They have 

 not crossed the Atlantic, but have come from 



