seemingly a mask, of the Roman king, Tarquin.

On the other hand, a certain species of mollusk is called Pupa, because its shell looks exactly like the pupa, or chrysalis, of an insect. There seems to be no end to imitations of the kind in nature. Dr. Dean, who jokingly refers to them as examples of "unnatural history," speaks of the fact that the "sphenoid" bone at the base of a rabbit's skull pictures the head of a fox, its arch enemy, with such striking accuracy that it has long been used as a scarf ornament by fox hunters in England.

Among recent volunteer contributions to the collections of the Smithsonian Institution was a "petrified oyster." looked very much like a real oyster, opened on the half shell; and, as if to complete the verisimilitude, it even contained a fossil pearl. But, as a matter of fact, the pearl was merely a "concretion," and the oyster itself was not an oyster at all, but a mineralogical freak.

Concretions often assume queer forms. A pebble in a stream gathers about itself

grains of sand until an odd-shaped lump is made. A favorite shape for such lumps seems to be that of a turtle, with four legs, a head, and a tail. Similar concretions of carbonate of lime or clay assume the appearance of petrified peanuts. If one of them be broken, there is revealed a small spiral "winkle" shell, which has served as a nucleus. An interesting counterfeit of this kind, forwarded to Washington not long ago, was an alleged fossil foot of a child, with a little stocking on, the latter showing signs of wear on the ball of the foot and on the heel.

In the rocks of the so-called Table Mounds, in Iowa, are many distinct prints of cloven feet. It was formerly supposed that the devil, or possibly some of his imps, had visited the place. But recent study of the subject has shown that the prints in question are merely impressions left behind by a mollusklike animal known to science as Pentamerus, ages ago, before the rocks had hardened at a period, that is to say, when they were merely so much mud on

sengers to the top of Mount Falcon.

At Silver Plume, Colorado, a mining camp which nestles in the bottom of clear creek canyon, some enterprising pro

swung back and forth from one of the mines, high up on the mountainside. So, instead of ore, the buckets now carry passengers during the tourist season, and

the pay per ounce has proved more profitable.

The supreme thrill in actual railroading, however, is provided by the Argentine Central Railroad, which a few years ago was used solely for carrying ore from the Waldorf mine, high up on Mount McClellan, a shoulder of Gray's Peak. Rev. E. J. Wilcox, one of the promoters of the mine, conceived the idea of converting the road into a passenger line. From Silver Plume the road ascends in a series of thrilling switchbacks to a height of more than 14,000

feet above sea level. This road is now the highest actual railroad in the world, having no cogs nor cables. The motive power is furnished by specially constructed mountain-climbing engines.

Such devices for the amusement of the summer tourist make the summer park scenic railways and chute-the-chutes seem tame in comparison. More "thrillers" are being planned, and Colorado, with more than two dozen mountain peaks over 14,000 feet high, seems able to supply all the scenic background that the promoters can ask.