could be measured satisfactorily. Very many trees seen and for these reasons not measured would materially swell the figures in the first two columns.

TABLE OF MAXIMUM SIZE ACCORDING TO TAPE LINE MEASUREMENTS.

This is certainly the largest, both in height and bulk, of all the trees of the Mississippi Valley. Its form is very variable, the

*Only one tree measured for height, and this by no means a large one. I have been told on the very best authority of trunks forty feet in circumference.

† I know of one, not measured by myself, thirty-two feet in circumference, and have been told of a stump in Posey County, Indiana, which around the top is thirty-seven feet in circumference.

The tallest cottonwoods are no doubt one hundred and eighty feet or more in height.

§ The tallest sweet gums are certainly 160-180 feet, perhaps much more in height, and with clear shafts of over a hundred feet in length.

trunk being sometimes a tall arrow-like shaft, equalling the finest Conifere in straightness and gradual taper, the first branches being ninety to a hundred feet above the ground; but oftener, on the other hand, it is short and bulky, ten, fifteen or even rarely twenty feet in diameter, and only fifteen or twenty feet high, where three or four gigantic trunks separate and rise into a lofty massive head. The tallest of these sycamores rise apparently for one-third their height above the tree-top level of the forest, and are thus probably not less than two hundred feet in height.

TULIP TREE (Liriodendron tulipifera).

The second tree in size and very commonly of the above dimensions. The finest individual found prostrate was one cut for lumber near Timberville, Wabash County,. Illinois; it measured one hundred and fifty-eight feet in total length, while the trunk was twenty-three feet in circumference three feet from the base, and eighteen feet in circumference at seventy-four feet further up, where the first branch grew; the trunk perfectly sound and symmetrical throughout.

One of the most symmetrical and majestic of all our trees; the trunk clean, straight and long, and the head spreading and slightly drooping, usually elevated sixty to ninety feet from the ground.

Also one of our finest trees; the trunk long and slightly tapering, though generally less straight than that of the pecan and "Spanish oak," and with the top less spreading.

Trunks of fifteen feet in circumference and forty or fifty feet long very common, so much so that in one locality in the "bottoms" five trees of this size stood within sight all at the same time in the thick woods.

The most stately and symmetrical of all our oaks; trunk straight and columnar and top massive and dense, reminding one in its appearance of the pecan. A more usual size is one hundred and fifty feet high, the trunk fifty feet long and fifteen feet in circumference four feet from the base.

The most massive, in proportion to its height, of all our oaks.

The tallest tree in proportion to its girth. The largest shafts are probably over one hundred feet, and the greatest circumference about seventeen or eighteen feet; while many trees no doubt exceed one hundred and sixty feet in height.

Though usually considered one of the "underwoods," this tree is not unfrequently of these dimensions in very rich woods.

FOSSIL INSECTS FROM THE ROCKY MOUNTAINS.

BY SAMUEL H.. SCUDDER.

*

SEVERAL years ago, Professor William Denton discovered in shales lying near the junction of the Green and White Rivers in Colorado (?), the first traces of tertiary insects on this continent. They were found in two distinct localities, sixty miles apart, the specimens from one place differing from those of the other, not only specifically, but also to a very great extent in the general character of the whole assemblage. Reports of these discoveries attracted the attention of those who afterward explored parts of the Rocky Mountain region, and repeated inquiries were made concerning the exact location of the insectiferous beds. These explorations have resulted in the discovery of more fossil insects in the same general region by Mr. F. C. A. Richardson, who accompanied Major Powell's exploring party, and by Dr. Hayden in some of his numerous and fruitful researches. The latter brought home only three specimens, two flies and an ant, but the collections of the former are more numerous and afford material for the present notice.

Some doubt exists as to whether the insects discovered by Prof.

*See Proc. Bost. Soc. Nat. Hist., xi, 117-118. A detailed and illustrated Report upon these fossils, which Mr. Denton kindly lent for a long period of examination, will shortly be published.

Denton were found in Colorado (as stated) or Wyoming Territory. Those now under consideration purport to come from the latter district, as stated in the subjoined letter to the editors, though far removed from the vicinity of Chagrin Valley or Fossil Cañon, the two localities explored by Professor Denton. About one hundred slabs, mostly of very small size, were brought away; these contain at least one hundred and seventy-five specimens, including in that number all the reverses. Of these specimens thirty-five cannot be referred with certainty to any subordinal group, since they consist merely of abdominal segments or blurred and distorted fragments, the affinities of which can only be rudely surmised. The remainder are referable to nearly forty species, belonging to the following groups, mainly arranged in the order of numerical superiority:

Of the Diptera, one-half the specimens belong to a single or possibly two heavy-bodied species of small size, which, although invariably wingless, are presumed to be so only by mutilation, since exceedingly few wings are preserved on any of the stones; of the other half, two-thirds are Tipulida or Mycetophilida

*"I discovered and collected the fossil insects on the Green River in Wyoming Terri tory on the line of the Union Pacific Railroad about forty miles this side (east) of Salt Lake City. Or, to be more precise, the locality is five miles west of Green River City and on the railroad track. The latitude and longitude as near as I can make out from very imperfect memoranda are as follows, Latitude 41° 40′ north, Longitude 109° 50' west. I had a short time previous found two very imperfect fossil insects but could find no strata nor spot where any number could be obtained. I was then with the courteous explorer, Major Powell, and left the fossils with him. I returned a short time after (on account of poor health), and, while looking for fossil fish and leaves, found a stratum some two or three inches thick exposed in a railroad cut from ten to twenty feet from the top rock or sandstone; the rock, as near as my memory will serve me, dips to the southwest at quite an angle. The shale or portion of the shale on which the insects are found runs in a circle from the northeast to the southwest, as if on the border of a small lake. I also noticed that the fish are not in a regular order as the insects, which cover a space about two feet wide and form a ring or belt around the lake as near as I could make out from the appearance. The fossil insects, fishes, leaves and fruit abound in that section but are being rapidly worked up, thanks to the diligence of our naturalists and the kindness of the Superintendent, Gen. Sickles of the Union Pacific Railroad, to whom I am greatly indebted.”—F. C. A. RICHARDSON, Pres. Chicago Natural History Society, Aug. 5, 1872.