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THE POPULAR SCIENCE MONTHLY. 



identical species as belonging to a former 

 Arctoga?al fauna. The action of the steady 

 increase of cold which characterized the 

 gradual inauguration of the Ice period 

 would have been to drive the insects south- 

 ward and mix the Arctogaeal with the then 

 existing ' indigenous ' southern species. 

 The summers of the middle Glacial epoch 

 probably afforded no opportunity for the ex- 

 istence of Noctuidae throughout the North- 

 ern States. On the decline of the Glacial 

 epoch, and with a steady increase of warmth 

 (still continuing), the species would progress 

 northward again. We may regard such a 

 species as Fidonia fimilaria G. & R., found 

 in Texas, as an outlying colony of F.fas- 

 ciolaria forced southward and retained by 

 local influences, and possibly having sub- 

 mitted to the modification which enables us 

 at this day to separate the two forms. Dur- 

 ing the Pliocene, the common ancestor of 

 the two forms may have been different from 

 either. During the Pleistocene, Holocene, 

 and Recent periods, we must consider such 

 species as Hadetia arctica to have preserved 

 their identity, while many may have per- 

 ished or submitted to modifications, and 

 these latter may be represented by the 

 closely-allied species of the two faunae. 

 The Glacial epoch may then supersede the 

 ' Atlantis " of those entomologists *who 

 looked for a geographical connection in 

 former times to account for the existence 

 of identical or representative species on 

 the two continents.'* 



The Pottery of the Mound-Builders. 



Prof. E. T. Cox, having examined a great 

 many specimens of potteries of the ancient 

 mound-builders in the Western States, has 

 never been able to find any evidence of 

 their having been hardened by fire, or even 

 sun-baked. The material employed is a 

 mixture of river-mud and, most generally, 

 pulverized mussel-shells, united in such 

 proportions as to make a cement which 

 hardens in the air, or on beicg exposed to 

 moisture, like the concrete of the ancient 

 Romans ; hence this ancient " pottery " is 

 in fact a sort of artificial stone. In chemi- 

 cal composition it agrees very closely with 

 the concrete made of ordinary cement- 

 stones. These facts lead to the conclusion 

 that the art of manufacturing concrete, or 



artificial stone, did not originate solely with 

 the ancient Romans, but that it was alike 

 understood by the earliest inhabitants of 

 America. As regards the mechanical pro- 

 cesses followed by these ancient artisans, 

 Prof. Cox says : " Though it is my opinion 

 that the so-called pottery of the mound- 

 builders was fashioned by hand, without 

 the use of a lathe, yet I am convinced that 

 the ancient pottery of Peru, and other 

 South American states, was largely made 

 of pieces formed by pressing the cement 

 into moulds, and these pieces were subse- 

 quently united together to form the entire 

 vessel. The lines of union are usually cov- 

 ered by a band, or some grotesque image. 

 The numerous tubercles and other raised or- 

 naments, which cover the surfaces of jugs, 

 vases, etc., could only have been formed 

 in this way. I do not, however, find any 

 pottery of the mound-builders that would 

 lead to the belief that their skill went so 

 far as to enable them to mould it in parts, 

 or to fashion it in any other way than by 

 the hands." 



A Primitive Fort. One of the most re- 

 markable works left by the mound-builders 

 is a stone fort in Clarke County, Indiana. 

 As described by Prof. E. T. Cox, this fort 

 stands upon the terminal point of a high 

 ridge, which is washed on its south side by 

 the Ohio River, and on the north by Four- 

 teen-Mile Creek. The point of the ridge is 

 pear-shaped, and the fortification includes 

 from eight to ten acres. The highest point 

 at the stem of the pear is 280 feet above 

 the Ohio, and is only 10 to 20 feet broad, 

 presenting almost a perpendicular wall to 

 the river. A natural wall of Niagara lime- 

 stone furnishes complete protection against 

 the approach of an enemy at the upper part 

 of the fort, with the exception of a short 

 gap on the creek-side, extending from the 

 upper point southward for about 100 paces. 

 This break in the natural wall is protected 

 by an artificial wall 75 feet in height, made 

 by laying up loose stone, mason -fashion, 

 but without mortar. The base, for 65 feet 

 in height, follows the slope of the hill-side, 

 and then rises 10 feet vertically. Around 

 the southern terminus of the point there is 

 an artificial stone-wall 10 feet high, which 

 connects the two natural walls of Niagara 



