to or very little beyond its tip; also by a sunken polished plate at the end of the body dorsally; the plate but sparsely covered with hairs, elongate, square in front and broadening behind. The legs have the terminal hooks very short and blunt, the front pair is longest, the second shortest. Hairs of body barbed, slightly curved and attenuated. The scissor-like mandibles are faintly toothed within. With age the color intensifies to scarlet, but the legs, palpi and ventral surface are always more pale and silvery than the superior part of the body. The male is smaller than the female, has more intense color, relatively somewhat longer legs, wih the body more pointed behind and more deeply constricted; the anal plate more narrow; ventrally his body is more distinctly constricted toward tip, and more deeply impressed longitudinally; also with the genital impression more distinct. His body becomes more creased and impressed with age, while that of the female becomes broader and more smooth and swollen. Average length of female when full grown about 3 mm.; male about 2 mm.

Widespread. We have it from Manitoba, Texas, various eastern States and from California.

In each of the two egg-masses we have examined, the number ranged between 300 and 400, the mass being irregularly globose, and the eggs but loosely adhering to each other. We have not been able to ascertain the exact length of time required for the full development of the larva after attachment, but it is brief and seldom exceeds a fortnight, while the final transformation after detachment occupies but three or four days. Though the motion of the swollen and detached larva is slow, the legs move about with considerable rapidity, yet in the gradual change to pupa they shrink and are partially drawn in. Since De Geer's time it has been known that some of the octopod mites are hexapods in their early life, and there can be no doubt but that all the Trom bidida have hexapod larvæ. In addition to the locust mite above described, we have found another larval form attacking the mature C. spretus. It is at once distinguished from the larva of locustarum by the more prominent head, by the longer, more slender legs which are 7-jointed, the joints increasing in length to the penultimate which is longest, and by the hairs, whether on the body, legs or palpi, being long, tapering and barbed. It is possibly the larva of a large species which we have called Trombidium giganteum, distinguished by the following characters:

Trombidium giganteum Riley.-Adult 8 mm. to 9 mm. long; pyriform, somewhat flattened; no pronounced constrictions, but

various dorsal irregularities, usually about five pairs of circular

α

Fig. 3. Trombidium giganteum; a, pedal claws; b, labial claw and thumb.

of

depressions connected by transverse ones on anterior two-thirds, and a triangular series posteriorly. Barbed hairs, long and tapering, but very dense and even. Color deep scarlet, the legs concolorous; eyes dark. Characterized by the penultimate palpal joint forming a single claw with a prominent notch, while the terminal thumb is large, extending one-third its length beyond the claw, clavate and with the inner side of its broad end flattened; the claw as well as the thumb. having sparse hairs; terminal joint of legs squarely docked, with the claws reaching but little beyond the side.

Living in the ground. Nine specimens examined. We have also reared to the perfect state the well-known Astoma parasite that attacks the common house-fly (Musca domestica) in this country.

The larva (Fig. 4) has the same mode of transformation as T. locustarum, but is much more active after detachment, while the gradual shrinking and withdrawal of the larval legs during the transformation to pupa is much more easily obFig. 4. Larva served. The species is distinguished from T. locustarum by the following characters:

Trombidium

muscarum.

Trombidium muscarum Riley.-Larva distinguished from that of T. locustarum by the greater relative length of legs, and by the hairs on the body being much longer and more conspicuous; also by the more distinct transverse sutures, of which there are four. Transverse striations noticeable soon after attachment. Full grown larva also more active. Pupa.-More rounded behind.

α

Fig. 5.-Trombid

ium muscarum; a, labial claws and

berculous hair.

Adult.-Average length 1.2 mm.; color bright thumb; b, pedal and pale scarlet; legs very pale and with the claws; c, barbed tu- terminal joint fusiform and the claws much longer than in T. locustarum, and more nearly as found in the larva; body rounded, very little narrower behind, with no impressions or other marks. Barbed hairs of body sparse, short, blunt and tuberculous, giving a beautifully sprangled appearance under the microscope. Genital depression circular; penultimate palpal joint ending in two small, equal, blunt claws, the thumb being very small, tuberculous, and not reaching its tip. No marked sexual differences.

Many specimens examined.

The mode of growth of these mites may be more clearly illus

trated by a brief reference to a common red water mite (Hydrachna belostoma Riley) which we have studied. The mites of the typical genus Hydrachna are, in reality, the aquatic representatives of Trombidium, and have a precisely similar mode of development. We have not had the eggs, but in Europe they are known to be laid in spring, in holes in soft-stemmed aquatic plants.

The young larva (Fig. 66) like that of Trombidium, is pale red, hexapodous, and with the legs 6-jointed, including the coxal joint. It has the mouth-parts retracted, and is characterized by two dark eye-spots anteriorly, and by the swollen second joint of

Fig. 6.-Hydrachna belostome; b, newly hatched larva; a, larva soon after becoming fixed; c, mature larva with pupa forming within; d, adult; e, its pedal claws; f, palpal claws of larva.

the palpi showing at each anterior corner. Moving about in the water these young larvæ fasten, often in very large numbers, to different aquatic insects. Water bugs of the family Belostomida are particularly subject to attack, and especially Zaitha fluminca (Say1), upon a single specimen of which we have sometimes counted over 500. They are able to fasten to the bug by means of several sharp hooks at the end of the palpi. Once fixed, the head and mouth parts stretch until they become separated by a neck from the main body, the transparent skin of which rapidly swells and elongates so as to form a bag with the more solid, dark-red parts visible anteriorly. (Fig. 6a.) The maxillæ penetrate and extend beneath the chitinous covering of the host, until they form a long pointed thread. The legs curl up, become useless, and are more or less withdrawn, and the larva gradually passes to the pupa state within this bag, which becomes more and more swollen and rounded posteriorly, and finally bursts to release the adult mite. This bag-like larva was looked upon as 1 Perthostoma aurantiaca, Leidy.

an egg by many old authors, and was made the type of the genus Achlysia by Audouin.

The adult swims actively about in the water, but before attaining maturity fixes to some plant and undergoes another molt without material change of form.

Hydrachna belostoma Riley.-Larva. Hexapodous. Ellipticovoid. Pale red, with two dusky eye-spots. Legs 6-jointed including coxa; terminal joint longest; claws very small. Surface closely and evenly studded with minute points. Palpi drawn beneath the head with the second joint greatly swollen, and showing like an eye at each anterior side of the body; the three terminal joints indistinctly separated and each armed with a sharp hook. Becoming elongate and more or less pyriform, with a distinct neck when fixed. Pupa formed within the bag-like body of larva. Adult-Average length when first from pupa 1.5 mm.; globular; color dark blood brown; body smooth; legs with but few hairs, terminal joint truncate and with two very minute claws; palpal claws very small and the thumb no longer.

NOT

THE HOME OF THE HARPY-EAGLE.

BY FELIX L. OSWALD, M.D.

OT far from the old military road which unites the Mexican seaport of Tehuantepec with the cities of the table-land, there stands an ancient Spanish fort, El Fortin de Tarija, which is now used as a storehouse by the proprietors of a neighboring coppermine, while one of the larger outbuildings has been converted into a tavern, where the stage coach stops for dinner. Posada de dos mares, Hotel of the two seas, seems rather a strange name for a posada situated in the heart of the Sierras, and at an elevation of at least twelve thousand feet above the level of any sea, but if the traveler deigns to alight and share the table d'hôte of the humble. posadero he may convince himself that the name is not so very inappropriate after all.

"Forty minutes time before the coach starts Señor," my host will observe after dinner, "and if you never passed here before, perhaps you would like me to accompany you to the Fort and show you the alta vista, the grand view, from the parapet."

“Grand view? is there anything exceptionally grand about it?" "Yes, sir, it is the grandest view in America, for you can see

los dos mares, the two oceans, at the same time! I only charge you one real (twelve cents) extra."

He who has never seen two oceans at the same time will very likely invest a real. The view is grand indeed. You stand on the back-bone of the American continent, which measures less than two hundred English miles from shore to shore here, and see the Gulf of Mexico so plainly that you might distinguish the smoke-trail of the New Orleans packet, or the glittering towers of St. Juan de Ulloa, while the Pacific, though thirty or forty miles nearer, glistens faintly through a gap of the Chiapas coasthills, and but for the sharp-drawn line of its horizon might be mistaken for a mountain lake. Yet it is not the water that constitutes the grandeur of the alta vista, it is the land, the mainland of the western world, of which you see a larger and fairer portion from the parapet of Fort Tarija, than from perhaps any other point between Mount St. Elias and the Peak of Aconcagua. Far from the north, from the distant border state of Sonora, descends a mountain chain which is easily recognized as the Sierra Madre, the main and central chain of the American continent, the southern prolongation of the Rocky mountains of New Mexico and Colorado. A second Sierra, a continuation of the California Contra-costa range, lifts itself in the north-western sky, and may from here be traced through a succession of fainter but snowier summits that seem to rise with the distance, till they culminate in a stupendous peak, the extinct volcano of Culiacan, which looms like a jagged white cloud over the edge of the horizon. About ten leagues, or thirty English miles, from the Fort the two Sierras unite, and between their icy ridges, their wild crags and their forests of evergreen pines enclose a mountainland which is perhaps, after all, the true paradise of the western hemisphere.

From the regions of eternal snow to the lakes and fruit-groves in the valleys that communicate with the primeval forests of the tierra caliente, this vast triangular terrace-land, the great mountain valley of Oaxaca, exhibits every degree of elevation, the climatic extremes with all their intermediate grades and almost every variety of the American fauna and flora. On a surface of six thousand English square miles the castern half of the state of Oaxaca unites a greater abundance and variety of animal and vegetable life than any other American country of equal extent,