difficulties encountered were greater than was expected, owing to the wind and the rarefaction of the air. On the top of the mountain the thermometer showed a temperature of 11° Fahr. There is no crater at all, but two peaks, both of which Mr. Whymper ascended; he found that the higher one was at an elevation of 21,982 feet above the sea-level, or nearly 12,000 feet above the valley of Quito.-English Mechanic.

-The American Academy of Arts and Sciences celebrated the first centennial since its foundation in Boston, on the 26th of May. This is the oldest scientific society in America next to the American Philosophical Society of Philadelphia, The formal exercises were held at the Old South Church, where Franklin was baptized; addresses being made by Hon. R. C. Winthrop, Ex-president Asa Gray and others. At the collation in the rooms of the academy, numerous delegates from home and foreign societies expressed their congratulations and good wishes. A large attendance crowded the hall of the academy.

- Died on the 5th Aug., Alvah James Ibbotson, aged 53 years. Mr. Ibbotson was a lithographic artist who stood at the head of his profession in this country. Most of the best plates of vertebrate fossils published by Leidy and Cope were his work, besides many plates of the fossil invertebrata published by Meek, White and others. He was remarkable for accuracy and artistic finish, as well as rapidity of execution. Mr. Ibbotson was a native of England, and had been in the employ of T. Sinclair and Sons, of Philadelphia, for twenty-five years.

A German naturalist, in the course of inquiries as to the phosphorescence of the sea, has found that the phenomenon occurs whenever sea fishes are brought into a three per cent. salt solution. The luminosity begins apparently in the eyes, spreads over the whole fish, and increases day by day. The fish after some time seems luminous throughout. The phosphorescent substance is a kind of mucus, which appears dirty-white by day, and shines in the dark.

- Mr. J. A. Lintner has received the appointment of State Entomologist, the office, discontinued after Dr. Fitch's death, having been again established. The appointment is a most fitting one, as Mr. Lintner is well known as an excellent observer and clear writer on economic entomology, besides having done a high order of work in general entomology.

WHAT the humming-birds are in our avifauna, the "darters" are among our fresh-water fishes. Minute, agile, beautiful, delighting in the clear, swift waters of rocky streams, no group of fishes is more interesting to the collector; and in the present state of their classification, none will better repay his study. Notwithstanding their trivial size, they do not seem to be dwarfed so much as concentrated fishes-each carrying in its little body all the activity, spirit, grace, complexity of detail and perfection of finish to be found in a perch or a "wall-eyed pike."

To the entertaining and instructive account of the sub-family given by Jordan and Copeland in former numbers of the NATURALIST,' I propose to add a few notes on their food, based upon a study of the contents of seventy stomachs, and to point out some of the correlations between structure and habit, with a view to accounting for the origin of the group.

These seventy specimens represented fifteen species, collected in all parts of Illinois, in several months of four successive years. They indicate much more than their number would imply, since from those collected at each time and place, as many were commonly studied as were necessary to give a full idea of the food of the species then and there. The different individuals from the

1" Johnny Darters." By D. S. Jordan and H. E. Copeland. AM. NAT., Vol. x, No. 6, June, 1876, pp. 335-341.

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The Sand Darter." By D. S. Jordan and H. E. Copeland. AM. NAT., Vol. XI, No. 2, Feb., 1877, pp. 86-88.

same date and locality usually agreed so closely in food, that the study of from two to five gave all the facts obtainable from several times as many. The data here given, therefore, really exhibit the food of the family at different seasons in twenty-nine localities within the State.

The genus Pleurolepis is comparatively rare in Illinois, as there are few of the sandy streams in the State, which it inhabits. Seven individuals were examined-four of P. pellucidus and three of P. asprellus. The food of these specimens was remarkably uniform-the only elements found being the larvæ of small diptera and Ephemerids. Eighty-one per cent. of the food of all consisted of the larva of Chironomus,1--a small, gnat-like insect,— twelve per cent. of the larva of other small diptera, and the remaining seven per cent. of Ephemerid larvæ (May flies).

Twelve specimens of the genus Alvordius were studied-seven of maculatus and five of phoxocephalus. These represented five

different localities and dates. This is a larger species than the preceding, and to this fact is probably due the predominance (seventy-five per cent.) in its food of the larvæ and pupa of May flies (Ephemerida). These included four per cent. of the larvæ of Palingenia bilineata Say, one of the largest Ephemerids in our streams. The remaining kinds were larvæ of dragon flies (Agrionini), four per cent.; larvæ of Chironomus, seven per cent., and Corixa tumida Uhl., thirteen per cent.

The genus Boleosoma, regarded by Dr. Jordan as the typical darter, was represented by twelve specimens from eight localities-nine of maculatum, two of olmstedi and one of camurum3 These specimens show but slight food differences from other darters of similar size; the only notable variation being the appearance of fifteen per cent. of case-worms (larvæ of Phry

1 The larvae of Chironomus are among the most important elements of fish food in our waters, appearing in abundance in the stomachs of the young of a great variety of species. They have been too little studied in this country to allow specific determination.

2 The classification used in this paper is that of the second edition of Jordan's Manual of Vertebrates.

3 Boleosoma maculatum and B. olmstedi should undoubtedly be united. Specimens in the laboratory collection present the extremes of both forms, together with numerous intermediate stages of each character used to distinguish them.

This whole group exhibits a surprising variability, perhaps due to its comparatively recent origin.

ganeida). Sixty-six per cent. of the food was Chironomus larvæ, seven per cent. larvæ of other minute diptera (including Simulium), and the remaining eight per cent. was larvæ of small Ephemerids.

I studied the food of two specimens of Pacilichthys variatus, four of P. spectabilis and two of P. asprigenis-making eight of the genus, representing six localities. Fifty-eight per cent. of small larvæ of diptera (forty-nine per cent. of Chironomus), thirty-two per cent. of larvæ and pupa of small Ephemerids, and ten per cent. of case-worms made up the entire bill of fare.

Percina caprodes, the largest of the group, departs from all the foregoing species by the introduction of crustacean food-thirty per cent. of Entomostraca and three per cent. the smallest of our Amphipoda, Allorchestes dentata (Smith) Faxon. Most of the Entomostraca were Cladocera, including Daphnia, Eurycercus and Daphnella.1

Here occurred the only instance of molluscan food in the group. One specimen had taken a few individuals of Ancylus rivularis Say. Reduced ratios of Chironomus and Ephemerid larvæ, and a few Corixa tumida complete the list.

Of Nanostoma zonale, less common than the others, but two individuals were examined, and these had eaten nothing but larvæ of small diptera, including sixty-five per cent. of Chironomus.

Six specimens of Etheostoma flabellare var. lineolata, from four localities, had eaten sixty-one per cent. of Chironomus larvæ, twenty-seven per cent. larvæ of small Ephemerids, and twelve per cent. of Copepoda (Cyclops).

Boleichthys elegans, found only in the southern part of the State (three specimens examined), had eaten only dipterous larvæ (thirtyseven per cent.) and Ephemerid larvæ (sixty-three per cent.). This is a larger, heavier species than most of the others, and, therefore, like Alvordius, prefers Ephemerids to gnats.

Last and least comes Microperca punctulata, represented by nine specimens from four localities in Northern Illinois. This smallest of the darters shares with Percina, the largest, the peculiarity of crustacean food, which made up sixty-four per cent. of the total. The principal kinds were Cyclops, Chydorus, young

1 Daphnella was found in a Percina from the Calumet river, at South Chicago, but not in condition to permit the determination of the species.

Gammarus fasciatus Say, and young Crangonyx gracilis Smith. The remaining elements were Chironomus larvæ (thirty-four per cent.) and a trace of Ephemerids (two per cent.).

It will be seen that the family, taken as a whole, divides into two sections, distinguished by the presence or absence of crustacean food. This is easily explained by the fact that Percina and Microperca range much more freely than the other genera-being frequently found among weeds and Algæ in comparatively slow water with muddy bottom, while the others are rather closely confined to swift and rocky shallows.

In discussing the food of the whole group, taken as a unit, it may best be compared with the food of the young of other percoids. It is thus seen to be remarkable for the predominance of the larvæ of Chironomus and small Ephemeridæ―the former of these comprising forty-four per cent. and the latter, twenty-three per cent, of the whole food of the seventy specimens. In young black bass (Micropterus pallidus) on the other hand, the averages of nine specimens, ranging from five-eighths inch to one and a half inches in length, were, in general terms, as follows: Cladocera forty-two per cent., Copepoda seven per cent., young fishes twenty per cent., Corixa and young Notonecta twenty-nine per cent., and larval Chironomus only two per cent. The search for the cause of this difference leads naturally to an examination of the whole economy of these little fishes, and opens up the question of their origin as a group.

The close relation of the Etheostomatina to the Percida proper, requires us to believe that the two groups have but recently diverged, if, indeed, they are yet distinctly separate.

We must inquire, therefore, into the causes which have operated upon a group of percoids to limit their range to such apparently unfavorable situations, to diminish their size, to develop unduly the paired fins and reduce the air-bladder, to remove the scales of several species more or less completely from the head, breast, neck and ventral region, and to restrict their food chiefly to the few forms mentioned above.

No species can long maintain itself anywhere which cannot, in some way, find a sufficient supply of food, and also protect itself against its enemies. In the contest with its enemies it may acquire defensive structures or powers of escape sufficient for its protection, or a reproductive capacity which will compensate for