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meter, light may be sent through them from an aperture of known diameter, and a piece of card or ground glass placed between the lenses at different points to indicate the course of the rays. For measurements, one of J. Moller's photographed micrometers, inserted as an object, is most convenient, the dense black blocks admitting of accurate reading, and the millimeter being a more convenient unit than the line. The magnifying power is ascertained according to the ordinary formula: Divide the product of the focal lengths by their sum diminished by the interval between them; e. g., for the first in the table 30x60-1800, which, divided by 30+60-58=48, the result being slightly too large.

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(All distances in millimeters except in the column marked "inches.")

By inspection of the table it will be seen that in half the oculars examined the ratio of focal length of eye lens to field lens is about one-half, in only one is it one-third, and in one of older construction they approach so near as seven-ninths. The general principle in regard to the interval separating the lenses is that it shall be less than the solar focus of the field lens though in the deeper oculars, and in the orthoscopic, this limit is approached or slightly exceeded. But it must be remembered that in combination with the objective the ocular receives diverging rays, and hence the actual focus of the field lens for such rays is beyond the eye lens. In the shallow oculars it'will be seen that only the central portion of the eye lens is used.-W. H. Seaman (abstract) in Nat. Mic. Congress.

SCIENTIFIC NEWS.

In a recent letter to Dr. Hayden, M. de Lapparent, President of the Société Geologique de France, writes that the Geological Society of France has resolved to celebrate the fiftieth anniversary of its foundation. This should properly occur on the 15th of March, but as the annual meeting takes place April 1st, the Society has decided that the two meetings shall take place at the same time. A report will be read of the part which the Society has taken in the geological progress of the last fifty years. After the meeting a banquet will be given by the French members of the Society to the foreign geologists who have been so good as to respond in person to the invitation to be present. M. de Lapparent speaks of the pleasant relations established with foreign geologists by the meeting of 1878, and hopes that these relations will be further increased in 1880, and that much may be done to render the meeting at Bologna, in 1881, still more interesting and important.

-The dispute between the Directors of the Park Commissioners and the Permanent Exhibition Company of Philadelphia. having been settled to the satisfaction of both parties, the latter will at once proceed to carry out its plan as a combination of museums. The close of last year saw a balance of $16,000 in its treasury, and it is believed that next year a considerable increase in the fund available for scientific purposes, will be made.

- Mons. A. Robin (Préparateur à la Faculté des Sciences), Rue d'Ulm, 38, Paris, France, is now preparing a general work upon the anatomy of the Chiroptera, and wishes to obtain, either by exchange, or otherwise, American material in this order of mammals.

- According to the Academy, C. Kegan Paul & Co., London, have published a memoir of the late Dr. Phillip P. Carpenter, well known as an able naturalist as well as philanthropist and sanitary reformer.

- The Academy of Science at Turin has awarded a prize, amounting in value to about £480, to Mr. Charles Darwin for his discoveries in the physiology of plants.

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PROCEEDINGS OF SCIENTIFIC SOCIETIES.

NEW YORK ACADEMY OF SCIENCES, February 16.—Dr. R. P. Stevens remarked on the geology at the head of the Ten-mile branch of the Blue river, Colorado, and Mr. W. E. Hidden. exhibited and described two new meteorites from the Southern States.

March 1.-Prof. E. C. Spitzka made a communication on the brain of man and of the ape, their resemblances and their differ

ences.

BOSTON SOCIETY OF NATURAL HISTORY, February 18.-Mr. E. R. Benton spoke on the Brighton "amygdaloid," and Dr. Wm. M. Davis on the stratified amygdales in the Brighton amygdaloid, while Prof. N. S. Shaler remarked on the origin of the various classes of lavas.

March 3.-Prof. G. H. Stone read a paper on the kames of Maine.

MIDDLESEX SCIENTIFIC FIELD CLUB, Malden, Mass, January 7. -Prof, E. A. Dolbeare, of College Hill, Mass., read a paper on radiant energy and its effects. Radiant energy, with Prof. Dolbeare, is synonymous with the terms heat, light, etc.

February 4.-Herbert A. Young, of Revere, Mass., read a paper on insectivorous plants, illustrated by diagrams.

CALIFORNIA ACADEMY OF SCIENCES, Jan. 11, 1880.-President Davidson in the chair. Mr. B. B. Redding read a paper on "The Buried Treasures of our Remote Ancestors." Prof. Davidson made a verbal communication announcing the results of the Coast Survey Expedition for the observation of the late Solar Eclipse.

Feb. 2.-President Davidson in the chair. Mr. Stillman read the chemical analysis of a secretion of the Parrya mexicana, the greasewood or creosote plant, caused by the puncture of an insect; also analysis of the oil of the California laurel or bay tree. J. P. Moore announced that a catalogue of the Fungi of California was about to be published by Dr. Harkness under the auspices of the Academy. Dr. Behr read a paper on the gradual change of the Flora of the San Francisco peninsula, and on the supplanting of the native growths of all countries by those of Europe and Africa, especially the former.

March 1.-Prof. David S. Jordan gave an account of the labors of the Fish Commission on the Pacific coast. Prof. Stillman read an article on the gum and coloring matter found on Acacia greggi and Larrea mexicana. There was a discussion on the Metric System.

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SELECTED ARTICLES IN SCIENTIFIC SERIALS. THE CANADIAN ENTOMOLOGIST.-February. On certain species of Satyrus, by W. H. Edwards.

THE GEOLOGICAL MAGAZINE. - February. Mr. Hill on the cause of the glacial epoch, by James Croll.

ANNALS AND MAGAZINE OF NATURAL HISTORY.-February. On some blind Amphipoda of the Caspian sea, by Dr. Oscar Grimm.

Zeitschrift füR NATURWISSENSCHAFTLICHE ZOOLOGIE.—January 23. On the development of the skull of the salamanders, by Ph. Stöhr. On the central nervous system of the crayfish, by K. R. Krieger. On the convolutions of the cerebral hemispheres of the zono-placental mammals, by J. Krueg.

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BY EDWARD BURGESS.

VERY one knows that butterflies and moths, the insects forming the group Lepidoptera, often feed on honey, and that for the purpose of obtaining it, they are provided with a long trunk, or tongue as it is sometimes called, to reach the nectaries of flowers. Sometimes this trunk is very long, in the case of our common tomato caterpillar moth, for example, its length is three inches, while in some allied moths of tropical regions it is greatly longer, and botanists and entomologists have often pointed out the relation existing between the length of various long-tubed flowers and of the trunks of some species of moths in the same region.

Thanks to the acuteness of Savigny, entomologists have long known that this trunk is not an organ sui generis, but simply the metamorphosed maxilla, or second pair of jaws of biting insects, which have become specialized to form a sucking tube. The mandibles or first pair of jaws, which, while the insect was in the caterpillar stage were well developed to bite off pieces of leaves or other substances then its food, are, in the perfect butterfly, reduced to the merest rudiments (Fig. 1, md), only to be found by carefully brushing away the thick covering of scales and hairs. The pair of maxillæ, on the contrary, grow each into a long, gently-tapering organ with a deep groove along its inner surface; which surface being applied to that of the opposite maxilla, and held in this position by a sort of dove-tailing lock, there is formed a hollow trunk through which liquid food can be drawn into the mouth.

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When not in use the trunk is coiled into a close spiral, and lies beneath the insect's head, hidden between the large and hairy

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ach," so called, or perhaps in the peristaltic contraction of the trunk, or that simply the capillary action of the latter might be sufficiently powerful to dispense with any special sucking apparatus. The anatomy of the trunk has been equally neglected and misunderstood. Thus even Burmeister believed that each half had a canal of its own, and Newport described non-existing horizontal muscles, and otherwise mistook the muscular mechanism.

Having been for some time engaged in studying the anatomy of the "emperor," as Mr. Scudder has christened Danais archippus, our largest and very common butterfly, I will describe the mouth organs of this species, the same plan of structure prevailing through the whole group of Lepidoptera, at least wherever I have examined repre

sentatives.

FIG. 2.-Tip of In the "emperor" then, the trunk is about fiftrunk of D. archippus from out. teen millimeters long, with a width at the base of side, greatly mag- about 2 mm., from which it gradually tapers to a nified. The rings are really black point at the tip. Externally a sort of coat-of-mail and opaque, the intervening appearance is given by its composition of an imspaces delicate mense number of rings (Fig. 2) (or rather portions and transparent. of rings, the inner segments being of course wanting) which being united by more yielding parts of the cuticle, evidently permit the rolling up of the whole organ, while imparting at the

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