620 



CrraSurp cf Natural l^ts 



hut the term Simla is no longer used, except 

 by some modern naturalists to the Orang- 

 outang. [See APE, MONKEY, &c.] 



SIMULIUM.or SAND-FLY. An extreme- 

 ly troublesome Dipterous insect, respecting 

 which, in its different stages, Mr. Newman 

 furnishes the following information: 

 " The eggs of the Simulia or Sand-flu appear 

 to be at present unknown ; there is, however, 

 little doubt that, like those of other gnats, 

 they are deposited on the surface of the 

 water, and in that situation are hatched by 

 the warmth of the sun combined with the 

 moisture of the water. The larva is found 

 on the stems of water-plants (Phcllanclrium, 

 &c.), on those portions which are always 

 covered by the water. It is long, cylindri- 

 cal, considerably thickened posteriorly, and 

 nearly transparent ; its head is distinctly 

 separated from the body, and is of an oblong 

 form ; it has four jaws moving horizontally, 

 I each bifid at the tip, and two little horns in 

 the usual place of antennae, inserted in the 

 front of the head, rather towards each side : 

 each of these is composed of two joints, the 

 first or basal joint stout, the second or apical 

 one divided into many rays, which fold back 

 on the first joint : there are two very small 

 eyes on each side of the head. The body of 

 the larva is divided into twelve segments, 

 besides the head ; of these, the second is in- 

 crassated, and furnished below with a retrac- 

 tile conical foot ; the last segment is very 

 minute, and furnished with two small pre- 

 hensile feet : the air-tubes, so very plainly 

 seen in other aquatic larvae, are totally 

 wanting ; neither is there the least appear- 

 ance of spiracles or breathing -holes in the 

 sides. 



" The motion of the larva in the water is 

 tolerably brisk ; but on any object coming 

 in contact with it, it instantly becomes mo- 

 tionless, attaches itself by the anterior pre- 

 hensile foot, and remains for a long time 

 perfectly still and immovable. When it 

 moves from one place to another, its progres- 

 sion is undulating, somewhat like that of a 

 leech, being performed in this manner : 

 the anterior foot is firmly attached to some 

 object, then the posterior pair of feet are 

 brought up to it, the back arching up during 

 the operation ; the anterior foot then releases 

 its hold ; the body is again elongated, the 

 foot attached further on, and the posterior 

 feet again brought up to it. The food of the 

 larva is unknown : when full grown, it spins 

 a little silken sheath, in shape like a watch- 

 pocket, which is attached to the plant fre- 

 quented by the larva, and in this it shortly 

 changes to a pupa in an upright position : 

 the case being always open at top, the head 

 and shoulders of the pupa are seen project- 

 ing above it. The pupa much resembles 

 that of a moth : it is perfectly motionless, of 

 a brown colour, and exhibits very distinctly 

 the parts of the perfect insect through its skin : 

 from the back of its head arise, on each side, 

 four hair-like appendages ; these are tubular, 

 and appear to be designed for breathing. 

 About the 6th of July the little creature 

 bursts from its sheath ; the case of the chry- 

 salis opens in a right line down the back, 



and the perfect insect emerges through the 

 opening, surrounded by a bubble of air, and 

 slowly begins to unfold its wings under the 

 water ; finally, its skin being cast, and ma- 

 turity attained, the imago disengages itself 

 from its former habitation, and mounts 

 within its bubble to the surface of the water, 

 when the bubble bursts, and the creature, 

 with its new organs, has acquired a new 

 element. The imago is a small black fly, 

 with two large transparent wings, which, 

 when at rest, repose horizontally on its back ; 

 moderately long legs, and short stout an- 

 tennae : it flies with ease, and somewhat 

 sportively, rising and falling. In thiscountry 

 it is found in the damp parts of woods, and 

 other similar situations ; but, happily, in 

 very limited numbers." " The Simnlittm 

 seems to have adopted the world for its 

 country : no known land appears to be 

 without it; all temperatures suit it the 

 polar snows and the blaze of tropical sands. 

 Yet all the flies of which travellers complain 

 as so dreadfully annoying, are not Simulia ; 

 many of our commonest gnats have a 

 similar taste for blood. Although, from what 

 is related, there can be no doubt that the 

 blood of man is an acceptable food to the 

 Simulia, yet it is remarkable that the great- 

 est multitudes of these creatures inhabit 

 those bleak, inhospitable, and almost inac- 

 cessible regions where the foot of man seldom 

 treads, and where other warm-blooded ani- 

 mals are scarcely known to exist. It is 

 clearly ascertained that the female Simulue 

 alone suck the blood of man ; the males 

 spend their lives among the leaves of trees, 

 or settle on flowers, from which they appear 

 to derive nutriment ; it is therefore far from 

 impossible that, on the failure of animal, the 

 females may also have recourse to vegetable 

 food." Hist, of Insects. 



SIPHONAPTERA. A name given by 

 Latreille to an order of insects, including 

 those Apterous species which have a mouth 

 in the form of a siphon. 



SIPIIONAKIA. A genus of Mollusca, 

 the shell of which greatly resembles the 

 Patella in shape. The animal has no ten- 

 tacula or visible eyes. They are found on 

 the coasts of South America, Australia, and 

 in the Mediterranean. 



SIPHONOBRANCHIATA. The name 

 of an order of Gasteropodous Mollusca, in- 

 cluding those in which the branchial cavity 

 terminates in a tube or siphon, by which the 

 respiratory current of water is received and 

 expelled. 



SIPHONOSTOMA. An order of Crus- 

 tacea, all of which are parasitic upon Fishes, 

 aquatic Batrachia, &c., comprehending those 

 which have a siphon-shaped mouth for suc- 

 tion. 



SIPUNCULTJS. The name of a genus of 

 worms which conceal themselves in the sands 

 of the sea-shore, and occasionally protrude 

 their heads from the orifice. They are much 

 sought after by the fishermen, who use them, 

 like the Common Lob-worm (Arenicola 

 Piscatorum), as baits for their hooks. Some 



