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to reach with her head to the extreme lower end of her follicle, causing, in doing so, the narrow elastic portion of the follicle to bulge, and the orifice to open more or less, as it repeatedly did while the larva was yet feeding, whenever the excrement had to be expelled. Fig. 2, a, shows a follicle cut open so as to exhibit the elongated puparium, and the female extended from it as she awaits the male ; b, represents this degraded female more in detail. cursory examination of the male shows the genital armature, which is always exposed, to consist of (1) a brown, horny, bilobed piece, broadening about the middle, narrowing to and notched at tip, concave, and furnished with a tuft of dark hairs at tip inside ; (2,) a rigid brown sheath, upon which play (3) the genital hooks or clasps, which are also concave inside, strongly bifid at tip, the inner finger furnished with hairs, the outer produced to an obtuse angle near tip, and generally unarmed, (Fig. 3, e). In repose, this

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FIG. 3. THYRIDOPTERYX EPHEMERÆFORMIS: b, the end of male abdomen from the side, showing genitalia extended; C, genitalia in repose, ventral view; d, do., dorsal view ; e, tip of bifid clasp; j, tip of penis; all enlarged.

armature appears as in Fig. 3, 6, from beneath, and as at d, from above, and is well adapted to prying into the opening of the follicle. The male abdomen is telescopically extensile, while the tip easily bends or curves in any direction, but most naturally beneath, as at b, where it is represented enlarged about six times, and with

all the genital parts expanded; k, the fixed outer sheath; f, the clasps; g, a pale membranous sheath, upon which the præputium (h) plays, as on the finger of a glove; i, the fleshy elastic penis, armed with retorse hairs, and capable of extending to nearly onefourth of an inch; j, showing the end still moře fully enlarged. With this exposition of details, not easily observed or generally understood, the act of fecundation is no longer a mystery.

"Experiments made in 1878 led me to conclude that parthenogenesis, although not improbable, seldom occurred in this species. In some sixty instances where I excluded the males, the females either worked out of their follicles and dropped to the ground without ovipositing, or else died and dried up in the ends of the same, likewise without laying. I have found the same to hold true in those exceptional cases (four have already come under my notice) where, in a state of nature out of doors, the larva had undergone its transformations head upward. In every instance the poor female had worked out of the puparium and butted against the closed end of the follicle, perishing finally without laying, because the male could not reach her.*

“ The impregnated female that has laid her eggs always works out of her follicle when her task is completed, and drops to the ground exhausted; but she may at once be distinguished from those which perish without ovipositing by her shrunken, eggless body.

“ The fawn-colored down, which the female intermingles with her eggs, is composed of the silky hair rubbed from her body. If examined while yet in the puparium, and just before she would naturally issue therefrom, each ring of the body of the female is seen to be more or less clothed with this silky material, while the eggs are perfectly free from it until they are laid. Under the microscope, this covering is seen to consist of the most delicate fibres, many times finer than ordinary silk, and it is so easily detached that most of it rubs off and remains in the puparium on the partial issuing therefrom of the female."

* Since this was written more elaborate experiments have fully determined that parthenogenesis does occasionally occur in the species.

LIST OF PLANTS ADDED TO THE FLORA OF WASHINGTON FROM APRIL 1, 1882, TO APRIL 1, 1884.

By LESTER F. WARD.

(Read November 24, 1882.) [This list is supplemental to Ward's “Guide to the Flora of Washington and Vicinity” (Bulletin, U. S. National Museum). Unless otherwise stated, the species enumerated were found by the author.] 401. Argemone Mexicana, L. PRICKLY Poppy.

Above Georgetown, near the ice house. Dr. E. Foreman, June 17,

1883 89a. Viola canina, L., var. sylvestris, Regel. Dog VIOLET.

Left bank of Rock Creek below Pierce's Mill. First found and re

ported by Mr. Horace B. Patton, in April, 1883. Collected by

myself May 5, 1883. 93a. Viola tricolor, L. PANSY. HEART'S-EASE.

Reform School region, escaped and much reduced in size. June 25,

1882. 124a. Scleranthus annuus, L. KNAWEL.

Easby's Point. Theo. F. Streets, May 18, 1883. 142a. Hibiscus Syriacus, L. SHRUBBY ALTHÆA.

Escaped in many places. 1426. Hibiscus esculentus, L. OKRA. GUMBO.

Pierce's Mill road, near Tenallytown, Oct. 22, 1882. 208a. Desmodium ochroleucum, M. A. Curtis.

Mount Hamilton,* Dr. E. Foreman, Sept. 24, 1882. Should be col

lected before the middle of September. 234a. Phaseolus diversifolius, Pers. Wild BEAN.

Alexandria branch, B. & (). Railroad, above Uniontown, Sept. 10, 1882.

Also by Dr. Foreman near Roache's Run, Va. 304a. Callitriche Austini, Eng.

North of Mount Hamilton. June 24, 1882.

* The conspicuous hill opposite Mt. Olivet Cemetery, otherwise known as “Mulligan IIill” and “Munger's Hill,” is thus designated on Boschke's “ Topographical Map of the District of Columbia,” 1880.

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331a. Conium maculatum, L. Poison HEMLOCK.

Rhode Island avenue, on a vacant lot near 17th street. June 17, 1883. 333a. Cicuta bulbifera, L. WATER HEMLOCK.

Alexandria Canal, opposite the Arlington estate. Dr. E. Foreman,

1882. 391a. Eupatorium altissimum, L.

Between the canal and the river, a short distance below Chain Bridge.

First reported by Dr. Vasey and Dr. Chas. Mohr at the end of

September, 1882. Collected there by myself Oct. 5, 1882. 4360. Aster ericoides, L., var. villosus, Gray.

Woodley Park, Sept. 17, 1882. 457a. Pluchea camphorata, DC. Salt-Marsh FLEABANE.

Marshall Hall, Md. Collected by Mr. O. M. Bryan in 1883; speci.

mens sent to Dr. Foreman, and by him shown to me. 4974. Galinsoga parviflora, Cav.

Fourteenth street near G, July 25, 1882. First seen by Dr. Chas.

Mohr. Since observed by myself on Sixteenth street. 502a. Leucanthemum Parthenium, Godron. FeverFEW.

Park near B and Sixth streets. July 10, 1884. Canal road above George

town, June 17, 1883. 5040. Senecio vulgaris, L. COMMON GROUNDSEL.

Alexandria branch, B. &0. Railroad, a short distance above Union

town, May 27, 1883. 536a. Tragopogon porrifolius, L. COMMON SALSIFY. OYSTER-PLANT.

Nearly the same locality as the preceding. Dr. Foreman, May, 1883. 5439. Campanula aparinoides, Pursh. Marsh Bellflower.

Rock Creek. Mr. M. S. Bebb, 1863.

In preparing the “ Flora,” several species were admitted, which, though not yet seen by the author or any of the recent collectors, were yet vouched for by perfectly competent authorities who had themselves found them in earlier years. In harmony with the rule thus adopted, I now add, without hesitation, this species which Mr. Bebb informs me, in a letter, that he was in the habit of collecting in whilom days. From his description of the locality, I infer that

the spot on which the plant grew is now under cultivation. 628a. Lycopsis arvensis, L. SMALL BUGLOSS.

Near the Outlet Lock, Dr. Foreman, 1882. Collected there by myself

June 17, 1883.

629a. Heliotropium Europæum, L. HELIOTROPE.

Georgetown, near the Aqueduct Bridge, Mr. M. S. Bebb, 1863.

The above remarks on Campanula aparinoides apply equally to

this species. 640a. Cuscuta compacta, Juss. DODDER.

Specimen found in the herbarium of the Department of Agriculture,

collected near Washington by Dr. Vasey. 661a. Gratiola aurea, Muhl.

Specimen in my herbarium (wrongly labeled) collected on the Eastern

Branch marsh, in 1873. 732a. Scutellaria parvula, Michx. ScullcAP.

This species was simply overlooked in the catalogue. I have specimens

collected by Prof. Chickering near the Insane Asylum, May 26,

1875. 738a. Lamium purpureum, L. DEAD-Nettle.

Soldiers' Home grounds. I have fine specimens of this species which

I collected in this locality July 20, 1873, but had overlooked in preparing the catalogue. The omission was observed by Mr. Patton, who still found it there in 1882, and I again met with it

widely spreading through the grounds on May 20, 1883. 746a. Plantago pusilla, Nutt.

Near the southwest corner of the Soldiers' Home grounds (outside),

May 20, 1883. 773a. Polygonum tenue, Michx.

Mount Hamilton, Dr. E. Foreman, Sept. 24, 1882. Collected by my

self on both sides of the hill, Oct. I, 1882. 797a. Euphorbia mercurialina, Michx.

In a communication dated Dec. 6, 1882, the late Dr. George Engel

mann informed me that this species was once sent to him labeled

Washington, D. C., by Mr. F. Pech, who collected here extensively. 884a. Zannichellia palustris, L.

In the canal, above Foundry Run, June 17, 1883. 986a. Eriocaulon septangulare, With.

Eastern Branch (between tides) above Uniontown, Sept. 1o, 1882.

Abundant in the Potomac below Analostan Island, and near Custis
Spring,

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