Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/317

Rh SPIDERS.] AKACHNIDA 297 of the snare which is spun in the angles of walls, in crevices, between portions of detached rock, and other similar situations. The adhesive flocculus serves to en tangle insects, and makes them an easy prey to the spider who lies in wait not far off, having formed a funnel-shaped tube of slight texture from its place of concealment to its snare. With regard to the formation of the snares of the Territelarice, Mr Gosse has an interesting passage in A Naturalist s Sojourn in Jamaica ; it is, however, too long for quotation here. Mr Moggridge also (I.e. infra] has some details respecting the formation and repair of their nests by trapdoor spiders in confinement. The chief point of interest, however, in regard to trapdoor snares, is whether the hinged lid is formed in one continuous piece with the tube, and then cut out, leaving a portion unsevered to form the hinge, or whether the lid is made separately, except in that part intended for the hinge. Neither Mr Gosse nor Mr Moggridge enter into this question, though Mr Moggridge indeed speaks (l.c, p. 118) of his belief that, when all is completed, the spider cuts away certain threads by which the door is supported on either side of the hinge. The present writer was once told by a gentleman who had formerly resided in the West Indies, that trapdoor spiders there invariably make the tube and lid of one continuous, solid, homogeneous piece, and then cut out the lid with the falces. This account, especially as coming from a non-naturalist, seemed improbable a spider s falces being in no way, apparently, fitted for such an operation ; if, however, the fact be that the lid, instead of being of one solid piece with the tube, is merely connected with it by a few supporting threads (in accordance with Mr Moggridge s belief), these could easily be torn away by the spider s falces, and the lid would be left free, except at the point where the hinge is formed. CLASSIFICATION. It is impossible within our remaining space to go into detail upon this wide portion of the subject ; it must suffice to say that the order Araneidea may at present be divided into about thirty -two families. These are Theraphosides, Colophonides, Filistatides, QEcobii des, Tetrablemmides, Dysderides, Urassides, Palpimanides, Dietynides, Agelenides, Hersilides, Scytodides, I liolcides, Tlieridiides, Phoroncidides, Epe irides, Gasteracanthides, Uloborides. Mingrammopides, Poltides, Thlaosomides, Arcydes, Stephanopides, Eripides, Thomisides, Podophthalmides, Lycosides, iSphasides, Dinopides, Salticides, Myrmecides, Aphantochilides. In these families are comprised about two hundred and sixty 1 genera based upon special details of structure ; principally the position of the eyes, the form of the maxilhe and labium, the number and structure of the spinners, and some other details. The species are very numerous ; probably not a tithe of the existing ones are yet described. In one family alone, Salticides, nearly a thousand are known. As in all other creatures, differences of colour and markings, as well as integumental clothing and armature, serve to distinguish the species the latter, too, are at times of generic value ; but with regard to spiders particularly, in order to determine their species, it is very essential to obtain comparative dimensions from different portions of structure ; thus the position of the eyes on the fore part of the caput furnishes us with ic facial space (or the space between the margin of the caput just above the falces and the posterior eyes nearest to the medial line), and the clypcus, or the space between the same (fore) margin of the caput and the anterior eyes nearest to the medial line. The comparative extent of these parts is of great importance as specific characters, and they are easily observed ; that part of the facial space occupied by the eyes is concisely described as &quot; the ocular area.&quot; The relative and com parative lengths, again, of the legs, and of their different joints, are strong specific characters, the first also generic. Male spiders when adult may, with few exceptions, be certainly distinguished in regard to their species, by the form and structure of the palpi and palpal 1 No general work exists in which the families and genera of spiders are brought down to the present time, or in any degree near to it. The works of Walckenaer, Ins. Apt., and Koch, Die Arachnidcn, are out of date altogether in this respect, though still of great value and im portance in themselves. The work of Dr Thorell, On the Genera of European Sjnders, Upsala, 1870, is exceedingly valuable, but it only touches incidentally upon the exotic groups. organs, the development of the latter being an infallible criterion of maturity. Female spiders, again, may, in numerous cases, be as cer tainly distinguished by the form and structure of the genital aperture, situated in the medial line beneath the fore extremity of the abdo men ; this aperture is never externally &quot;perforate&quot; until the last moult of the spider, and its full development is therefore an unerring criterion of the maturity of the female sex. With respect to the senses of spiders smell and hearing nothing appears to have been certainly ascertained ; but the late Mr Richard Beck has an interest ing paper upon the subject in Entomologist, Lond. 1866, vol. iii. p. 246. He suggests that the fine and delicate hairs of some spiders legs may convey sounds to them. With regard to the sense of taste we may well conclude that spiders have this sense in considerable perfection, in the possession of a well-developed membranous tongue. GENERAL REMARKS. Spiders are to be found more or less abundantly in every part of the world and in almost every conceivable position; even subterranean caves, such as those of Adelsberg and the Island of Lesina, are tenanted by species peculiarly adapted by the absence of eyes to their dark and gloomy abodes. Less repulsive and forbidding in appearance than most others of the Arachnida, the Araneidea are often extremely interesting in their habits. Being almost exclusively feeders on the insect tribes, they are consequently endowed with proportionate craftiness and skill ; this is shown remarkably in the construction of their snares and dwellings. The &quot;trapdoor spider&quot; has always been one of note in popular works on spiders habits, and certainly the details of several different types of the trapdoor tubular nest, with the habits of the several species to which they belong, lately published by Mr Traherne Moggridge, 2 are of the greatest interest and importance. The typical trap door nest is a cylindrical hole in the earth excavated by the spider itself, lined with silk and closed by a lid, which fits like a valve or cork into the opening at the surface and opening by a strong elastic silken hinge, the spring of which closes it again with some slight force. Many spiders, however, live a vagabond life, and capture their prey without the aid of a snare, by springing on it unawares, or, in some cases, running it fairly down in open view; yet craft and skill are equally apparent, whatever be their mode of life and subsistence. To say that spiders are less repulsive and forbidding in appearance than other Arachnids, is to do them but scanty justice, for numbers of species of various genera notably among the Salticides, or jumping spiders are unsurpassed by insects of any order, in respect both to brilliancy of colouring and the designs formed by its distribution. Some of the curious and delicate little species of the genera Argyrodes and Ariamnes are perfect marvels of metallic brilliancy and beauty. These little spiders are found living as quasi parasites, in the outskirts of the webs of the larger exotic epeirids, and appear to live on the smaller insects caught in them; probably also spinning irregular snares of their own among the lines of the larger snare. In external appearance the young of spiders do not differ greatly from the adults, except in being generally more distinct in colour and markings ; in some species the characteristic mark ings can seldom be well traced except in immature examples. The cocoons or nests in which some spiders deposit their eggs are very beautiful, as well as varied and characteristic in form ; that of Ero variegata (BL), a little spider not uncommon in England, would arrest the attention of even an indifferent person; it is of an elegant pear shape, formed of a strong yellow-brown silk network, and attached by a long elastic stem, of the same material, to stalks of dead grass, sticks, or other substances, in shady places. An other, made by a larger spider, Agroeca Irunnea (BL), is of a truncated pear shape, formed of a continuous white silk fabric, and attached to blades and stalks of living grass and rushes, by a short pedicle; it must, however, be seen 2 Harvesting Ants and Trapdoor Spiders, Lovell Reeve, 1S72, with supplementary vol. 1874, illustrated with numerous plates. n. 3 8