Glacial striæ and polished surfaces at the head of Green Bay have a direction N. 34° E. coinciding with the axis of Green Bay. In the bay north of Sag and Burnt Bluffs, in Great Bay de Noc, they run about N. W. and S.E.

Among the glacial features may be mentioned the general aspect of the east shore of Green Bay and of Great Bay de Noc. Those deeply cut bays before mentioned must be regarded as of the nature of fiords, and doubtless owe their origin to spurs from the main glacier which excavated the Green Bay valley. The Sturgeon Bay spur was probably aided in taking its more easterly trend by a local glacier which contemporaneously descended the valley of the Uenominee. By their uniformity of direction a tendency is indicated in the main glacier to move in a more southerly direction than the general direction of Green Bay requires. In fact the islands between Port des Morts and Pt. de Tour exhibit the effect of intense glacier action in a direction N. and S. Long trails of detritus from these islands shoal the water for several miles southward; but toward the north the water becomes suddenly very deep.

A natural result of this spurring off from the main glacier is exhibited in the westward tendency of the coast line immediately south of the bays thus formed. The diversion of that portion of the moving glacier which passed through the valley of Sturgeon Bay would allow the extension of the opposing barrier of the Niagara limestone farther toward the west, thus bringing into view lower formations (Clinton and Cincinnati); and the spur which excavated Eagle harbor, acted in the same way to permit the existence of the point just west from the harbor on which the Clinton limestone is again exposed.

Another evidence of the more southward tendency of the main glacier consists in the fact that it actually broke through the Niagara barrier in numerous instances in a southerly direction, but did not once encroach upon the Trenton, on the opposite side of Green Bay, although it hardly rises above the water level.

We may therefore regard the fact established that the local glacier which excavated the valley of Green Bay, as far south as to include lakes Winnebago and Horicon in Wisconsin, was deflected from its N. and S. course by the escarpment of the Niagara limestone; and we must infer that its greatest force was felt where it first encountered it. We see the escarpment most demolished between Port des Morts and Pt. de Tour, and conclude that that interval must lie in the course of the original glacier. A course nothward thence carries us up the valley of Little Bay de Noc and the Whitefish river to the shore of Lake Superior. If we examine the south shore of Lake Superior, AM. JOUR. SCI-THIRD SERIES, VOL. II, No. 7.-JULY, 1871.

we find that in a line directly north from the head of Little Bay de Noc occurs the only break in the otherwise continuous rock barrier. Dr. D. Houghton, in his report to the Michigan Legislature in 1840, says that "an elevated range of hills," or in another place, "an elevated and very regular chain of hills stretches from Point Iroquois to the Pictured Rocks," from which place they "pass away from the shore southwesterly, and Dr. Houghton adds that "the western prolongation of this rock has not been determined." From the mouth of the Chocolate river, six or eight miles east of Marquette, to a point one-and-a-half miles east of the mouth of Train river, the shore is low and occupied with drift deposits, the usual rocky barrier of sandstone is interrupted and entirely wanting. Both to the east and to the west from this interval the shore of the lake is formed by the rocky rampart either of the Lake Superior sandstone on the east, or of the Huronian and other Eozoic rocks on the west. Although this barrier passes a few miles away from the shore east of the Pictured Rocks it is nevertheless a continuous barrier of "sandstone hills" which cause the Falls of the Taquomenon, 90 feet in height, and appear in precipitous cliffs at or near Iroquois Point.

Again, from the mouth of Chocolate river to the falls of the upper Menominee occurs, in general, the strike of the Huronian, and from the latter place to the head of Keweenaw bay, a right line would pass some of the highest primary knobs and through the head waters of some of the principal rivers of the Upper Peninsula of Michigan. This rough and elevated character continues westward to the Montreal river, near the western extremity of Lake Superior. It is therefore rendered probable that the last lingering glacier, which was able to prolong itself beyond the south shore of Lake Superior, passed through the gap which occurs north from the head of Little Bay de Noc. It has been repeatedly stated by geologists who have observed the glacial striæ about Lake Superior, that their general direction is N.E. and S.W. It is therefore a fact of special significance, that the grooves at and near the mouth of Chocolate river show a north and south direction. At a point two miles west of the mouth of Carp river, and a few miles east of Marquette, there are two systems of glacial grooves, one running north 55° east, and the other north 5° east. Mr. Desor says of these: "The latter are distinctly seen crossing the others, and are therefore more recent. Some of them are besides distinctly curved, as if the body which produced them had been deflected in ascending the slope, a peculiarity not yet observed elsewhere." On an island east of Dead river (near Marquette) there are also two systems of furrows, one running N. and S. and one N. 20° E., the latter being the more distinct

and sometimes taking the form of troughs four feet wide and two feet deep. These indicate that the continental glacier moved in a direction N.E. and S. W., forming the deepest furrows, but that the local glacier passed N. and S. It was also, doubtless, "deflected" from its course, and the opposition of the Huronian formation, which gives the coast great elevation and abruptly turns it north from this place, may be supposed to have caused that change in direction.

In relation to the country between the head of Little Bay de Noc and the shore of Lake Superior we may infer that a valley exists, or did exist when the glacial epoch was waning, connecting Lake Superior with Lake Michigan through Little Bay de Noc, and that the present outlet of Lake Superior is of comparatively recent date. Not only do the descriptions of this tract by Messrs. Foster and Whitney confirm that inference, but examinations made the present summer, by Mr. A. S. Wadsworth of the Michigan Geological Survey, almost directly demonstrate the former outlet of Lake Superior to have been through the Whitefish valley. There is a continuous valley with high drift banks uninterrupted, from the mouth of the Whitefish river to Lake Superior. Upon reaching the watershed which lies but little above Lake Superior and within twelve miles of the mouth of the Train river, the head waters of the two rivers interlock on an extensive flat and rocky bed from which the drift has been removed and piled up in continuous bluffs on either side. From the summit of these bluffs extend extensive "pine plains," toward the east and west. On this rocky bottom are traces of running water, spread over an area of many acres, consisting of the peculiar "pot holes," from which " many cords of rock" have been removed. There are also deep gorges and crevices worn smooth by the motion of water and drifting sand.

Thus it appears that not only was the outlet of Lake Superior through Little Bay de Noc up to the close of the Tertiary, but that it continued to exist there after the stratification of the drift. The curious excavation and piling up of the drift on either side of the Whitefish valley could only have been done since the deposit of the same, and the water-worn surface of the Trenton limestone, on the top of the water-shed, must have been produced since the dawn of the Terrace Epoch. The old Tertiary channel is still obscured by the drift, either to the east or west of the channel discovered by Mr. Wadsworth.

Ann Arbor, Mich., August 20, 1870.

* Foster and Whitney's Report on L. Superior, Part I, p. 205.

ART. IV.-Infusorial Circuit of Generations; by THEOD. C. HILGARD.

THE soft and "naked," transparent and really animal* forms here to be considered, have some very striking and peculiar features in common. Their bodies are delicate, transparent, gelatinous, granular, and evidently sexless, although studded with reproductive yolks and locomotive molecules of the most varied description. On contact with air, when drying up, they do not leave behind any coherent coat or tissue whatever; but so soon as they are affected by incipient exsiccation, at once, by some sudden internal commotion, as if melting away, they become liquid, and entirely dissolve into a "sauce" of quite uniform, hyaline molecules, about line in diameter. They are all evidently immature forms, subject to a vast cycle of progressive and retrograde developments and infinitely multiplying the molecular germs at every individual dissolution.+ A little salt, glycerine, or sugar destroys their present form; but they seem to be hardly affected by morphia or atropia, even in strong solutions.

It is this feature of the non-endurance in drying up, which renders it at once certain, that no such sarcode bodies can continue to exist in integro, when exposed to the full heat of summer, on a cracking dry tub, or on a roof, likewise as torrid as a blazing July sun can render it within four weeks. The same applies to all the confervaceous, palmellaceous, protococcous, desmidiaceous, etc., fresh-water spawns, of true Mosses; which, once collapsed by drought, rarely continue growth in a progressive sense. With the exception of their common "nostoc "phase (specially adapted to endure even excessive dryness) they

* i. e. exclusive of all the chlorophyll-endowed, silica-coated, and automatous, or cellular cell-like sarcodic bodies and also the clear and vibrionic forms which belong to the algoid bryaceous developments. They are partly classed as green "Infusoria," and also constitute the "Chlorospermen" of "Algæ."

The same doubtless applies to a small "Stentor Roe," seen hovering up and down in water taken from ponds, aquaria, etc. It is of a hazy white color, scarcely perceptible to the naked eye, and remarkable for never touching the surface. When placed under the microscope, in a drop exposed to air, this animal germ (in shape resembling a Cyprea or a coffee bean) is seen violently throwing open its "cloak" or mantle, exhibiting an intense ciliary (fingered) vibratory action, all over the interior surface. It then throws out hyaline constitutive brood-balls of various sizes, each endowed with the same "fingered" action-(as if "kneaded about in invisible hands)—and ultimately entirely flows apart into such fleshy cilia, only leaving the intestine behind.

This form of self-multiplying, serial chorophyll bead-strings enveloped in a foliaceous slime is common to Lichens (particularly the genus Collema) and various brooding-phases of the algoid (chlorospermous) moss-spawns. With the Lichens, the interual chlorophyll of their thallus often develops, as is well known, in similar bead-strings, borne on the end of colorless (fungoid) tissue-fibers; in a manner also represented in the anatomy of Blodgettia confervoides, in Harvey's "Nereis."

"revive" only by starting anew from very reduced, but immensely multitudinous constituent particles of their own, which perdure exsiccation. In the class of Fungi we meet with similar examples, as e. g. in the case of the yeast-plant, which can endure a considerable degree of exsiccation without impairing the vitality of those cell-contents, which actually exercise the fermentive energies and also consume the old cell-coat-(not common cellulose, by the way) in this process of reviving. Likewise, the vermillion, gummose (tubercularia) pimples on rotting Black Oak branches can endure a baking process in the burning sun, but still revive on contact with water. Its spicular "spermatia" (fusidium, resembling Naviculæ or magnetic needles) at once assume an oscillatory motion and swell up to the size of those didymous (trichothecium) spores which presently stand erect on pedicels, as a pink velvet, in the chinks of the bark and collapse at the first touch of the sun; while their ultimate subcortical development into a mature, "black enamel" Sphæria again perdures in the heat.

Both

Under the circumstances above mentioned, the rain water and dry dust carried by the wind to the roof, and thence collected into a perfectly dry tub, itself standing on a similar roof, within a few days was found swarming with all the minor phases of the Vorticello-planarian germ-developments. the bodies and the yolks or gemmæ of the latter occasionally become reduced, by spontaneous dissolution, into very minute particles, each in the wet state capable of resuming the regeneration of individual germs. Judging from analogy, it is but reasonable to suppose, that it is this reduced nubecular and molecular condition, which adapts them to last and survive in a dry condition, as we find it not only with the Fungi, but also in the case of the pruinose-pulverulent, primitive moss-spawns, all three agreeing in this feature of being "reduced to dust, out of which they are again resuscitated. This evanescent condition, however, where gelatinous particles of about' of a line diameter shrink alike to imperceptible dimensions, affords no pretext whatever for assuming identities, just because we ourselves lose the means of discrimination. Whenever the identity of substance is preserved, each of these various molecular organisms preserves its cyclar developments distinct from similar, corresponding ones as true species, so far as my observations go.

There being, at present, no comprehensive pictorial works available to fall back upon for reference, that are sufficiently correct, even in their designs, to identify the forms, allowance must be made for the liberties of comparison taken in the following descriptive representation of the most frequent infusorial processes.