July 21, 1893.] 



SCIENCE. 



33 



month of April, when the sun rises clear and the air is crisp and 

 frosty, go out upon the suburbs of a prairie town, away from the 

 usual noises of the village, and listen. In a few seconds, if you 

 <;an recognize the sound, you will hear, above everything else, the 

 male birds go " boom, boom, boom." This is not a sharp, shrill 

 cry, but a round, full, detonating cannon-like sound, w^hich may 

 be heard at long distances. It comprises three clear, distinct 

 musical notes, corresponding with the " do, si, do " of the diatonic 

 scale. The first two are quarter notes, and the last is drawn out 

 to a full note, and even a prolongation of that. Probably some 

 idea of it could be had from this representation : 



i 



Boo- Boo- 



B- 



This "booming" may be heard every spring along in March 

 and April, and sometimes till May on clear frosty mornings about 

 sunrise and for an hour or two afterwards ; and for that reason I 

 have sometimes from my own fancy called them "sun worship- 

 pers." It is worth an hour's walk to go out and see these birds 

 when engaged in their booming orizons. As 1 have heard thou- 

 sands of them booming at one time along in the forties and fif- 

 ties, and have cautiously crept up to within a few yards of them 

 when they were in plain view, let me try and describe them if 

 possible. 



The males have two neck tufts of feathers, two or three inches 

 long, one behind each ear, and ordinarily they lie down close to 

 the neck. Also on the sides of the neck and extending about 

 two-thirds of the length of it, are two bare patches of skin capa- 

 ble of being inflited with air until they show out on either side 

 as large as a small orange, and are nearly the color of an orange. 

 Now, the proceeding is something like this: The bird stands un- 

 •concernedly among his companions for a minute or so, and then 

 suddenly he spreads his tail to its fullest extent like a fan ; his 

 wings are spread and thrust down to the ground similar to a tur- 

 key gobbler's action; he walks around and about, rubbing his 

 wing feathers upon the ground, his feet go patting alternately so 

 rapidly you cannot count the motions, his head and neck thrust 

 forward horizontally, the two tufts of feathers ate erected like 

 two great horns, the bare skins on the sides of the neck are in- 

 flated and then comes "boom, boom, b—o — o— m." This is re- 

 peated every few minutes for one or two hours in the morning, 

 when no more is heard until near sundown in the evening. 



A SILK-SPINNING CAVE LARVA. 



BY H. 6AKMAN, LEXINGTON, KENTUCKY. 



In the Bulletin of the Essex Institute, Vol. XIII., 1891, I de- 

 scribed a singular larra from Mammoth Cave, which was com- 

 pared with larvae of the Dipterous genera Sciara and Chirono- 

 mous, to which it bears some resemblance. Since this larva was 

 discovered a lookout has been kept for other specimens in hope of 

 learning something of the adult, but thus far no additional ex- 

 amples have been seen. My search has been rewarded, however, 

 by the discovery of a second larva, very different from the first 

 but in its way almost as strange. Evidently it is a related insect. 

 I take it to he the young of some cave-inhabiting fly. 



Large examples measure 12.5 millimetres in length by 1 millime- 

 tre in greatest diameter. The body is composed of twelve somites 

 Ijehind the head, very distinct from each other and graduall.y 

 increasing in diameter from the first to the seventh, after which 

 they remain constant to the twelfth, which is only about one-half 

 the length of the preceding somite and not more than one-fourth 

 its size. The bead is very small, and is enclosed in a smooth and 

 shining crust of a pale yellowish brown color. The body ter- 

 minates in a double finger-like clasping organ. 



Oq a visit to a small cave near Lexington, Kentucky, some 

 'months ago my eye was caught by a glistening thread on the lime- 

 stone forming the side wall of the cavity, about four feet from 

 the floor. Thinking it was the trail left by a spider, I began to 

 follow it carefully, expecting by this means to come upon the 

 insect. Instead of a spider this larva was found, — a translucent 



slender thing which might easily have been overlooked even 

 when one was engaged in fullowing the thread upon which it 

 lived. A touch was sufficient to put it in motion, then a touch 

 at the opposite extremity would cause it to move backward with 

 equal address. But nothing would induce it to leave the thread, 

 and I have since learned that the heat from a burning candle ap- 

 plied to its body and destroying its life leaves it clinging to this 

 fragile object. Not even spiders show such tenacity in retaining 

 possession of their egg-cases, or webs, when in danger, and I 

 infer that the welfare of this larva is intimately associated in 

 some way with the silken path it makes along the face of the 

 rocks. The thread is always accupied by a single individual, and 

 may be a foot or more in length. I have found no examples 

 nearer the floor than three feet. 



The larva clings to its thread by means of pads provided with 

 very minute chitinous asperities. One such pad occurs at the 

 anterior ventral margin of the second, and another in the same 

 position on the third, som te. These form rather large transverse 

 rounded folds of the skin, covered posteriorly with dark denticles 

 in numerous short series. The fourth somite lacks the pad, but 

 on the ventral side and anterior margin of each of the succeed- 

 ing divisions is a pad of another form, these being broader but not 

 extending so far up the sides. When creeping an undulatory 

 motion passes along the body, the pads dragging it forward, 

 the posterior appendage apparently aiding by seizing the thread. 



The details of structure have not been thoroughly worked out. 

 In a general way the head is like that of the larva described in 

 the Bulletin in 1891, but the large ocellus-like smooth areas of 

 the Mammoth Cave larva are not present in this, although I find 

 smaller oval areas surrounded by black rims and accompanied by 

 pigment spots, which appear to represent these structures. The 

 mouth parts are much like those of larval Sciara. The palpi 

 which project from the under side of the head spring from the 

 maxillae. In very young examples I can make out large ducts 

 which convey a secretion of some kind (doubtless the material of 

 which the silken fiber is composed) to the under side of the head. 

 No outward trace of respiratory organs is apparent. Four dark- 

 brown Malpighian tubules can be seen, through the body-wall, 

 opening independently into the intestine. 



On the dorsal middle line near the anterior margin of each of 

 the somites 8 and 9 is a turret-shaped prominence, the nature of 

 which I have not determined. The top is sometimes a trifle im- 

 pressed as if there were an opening to a gland beneath the skin. 

 They can not be stigmatal prominences, for these are always 

 paired. A study of sections may yield an explanation of them. 



The habit of living upon the side walls of the cave is probably 

 a means of avoiding enemies. Few of the predaceous cave 

 species would find the larvae there. The only available food 

 would seem to be occasional tallow drippings and the molds grow- 

 ing on them. 



Silk spinning is not general among Dipterous larvae, but the 

 cave species is not peculiar in this regard. I suspect that the 

 Mammoth Cave larva produces a thread also. Among ordinary 

 Diptera the clover midge {Cecidomyia trifolii) occurs to me at 

 this moment as an example of species which produce material in 

 the nature of silk. It envelops itself in a rather tough papery 

 cocoon when ready for pupation. 



A VERY bright comet has suddenly appeared in the western 

 sky, and is attracting attention from the unexpected manner in 

 which it has presented itself. The object from present accounts 

 was first seen on the 8th inst., by persons living in Utah and 

 Wyoming. It is very bright, about of the second or third magni- 

 tude, and has a tail that has been reported to be from five to twelve 

 degrees in length. The comet is moving very rapidly to the 

 east, and the only orbit at hand, at present, indicates that it is 

 now passing away froai the earth and will diminish very rapidly 

 in brightness. 



