210 



THE POPULAK EDUOATOE. 



of his love. Since the spinning faculty is that which is most 

 intimately connected with our idea of a spider, it was extremely 

 natural that the old Greeks should make the spider represent a 

 woman. Despite its false fame of ugliness, we, who call single 

 ladies spinsters, naturally associate the spinder, or spider, with 

 them. Unfortunately for the reputation both of spiders and 

 women, we cannot stop short in admiration of the art displayed 

 in the construction of the web, but the mind runs on to the 

 design and uses for which the art is employed. These designs 

 are to ensnare and to destroy. Hence deceit and cruelty, the 

 vices of the weak, have been attributed to spiders. The bitterest 

 satirists of the fair sex have found in the spider a simile which 

 has pointed their invective from the earliest ages of literature. 

 Thus, in one of the most famous tragedies of J^schylus, when 

 the chorus find Agamemnon slain in his bath by his deceitful 

 wife Clytasmnestra, they exclaim 



" Keiffai S'apaxcTjs ei> iKpaff^an Ta>8' 



a<re/3ei Qava.ru> fiiov e/cTn/ecoj'." 

 ("Thou in the female spider's toils art lying, 



And breathest forth, thy life, dishonoured dying.") 



Since the spider is the type of the class, we shall first call 

 attention to the character which it possesses in common with 

 the whole class Arachnida ; then proceed to describe the struc- 

 ture of the common spader in detail ; and finally notice the varia- 

 tions of this type in the different divisions of this class, such as 

 scorpions, mites, etc. 



The Arachnida are articulated animals, whose bodies consist 

 of a longitudinal series of segments like those of insects. This 

 segmentation into rings is, however, often less marked than in 

 insects, and in the true spiders, which have a smooth soft integu- 

 ment, the divisions are rather inferred, from tracing them in allied 

 forms or in the embryonic state, as they become more and more 

 obliterated, than from any indication of their actual presence in 

 the adult animal. In all cases they are distinguished from in- 

 sects by having no marked division between the head and thorax. 

 Both these divisions are combined, as in the higher crustaceans, 

 into one piece, called the cephalo-thorax. In the mites a still 

 further amalgamation of the divisions of the body into one 

 globate bag occurs, which represents at once head, thorax, and 

 abdomen. Where there is a constriction between the thorax 

 and abdomen, so that one can be distinguished from the other, 

 the limbs are wholly confined to the thorax. This distinctive 

 feature cuts them off from the Myriapoda and Crustacea. The 

 Arachnida never possess wings, and instead of the three pairs of 

 legs of insects, they have four pairs. These limbs are all jointed, 

 but they are built upon a somewhat different type to those of 

 insects, as we shall find when we come to describe them more 

 minutely. 



They have no antennae for the purposes of touch. These, 

 however, are probably represented by the great poison-jaws. 

 These jaws are so utterly different in form and function from 

 the feelers of insects that it is only by a careful examination, 

 combined with a good deal of speculative reasoning, that they 

 have been identified with them. Thus the absence of antenna 

 (in the proper sense) is a good distinctive character. Other 

 jaws, situated further back, are possessed by the Arachnida, the 

 most distinctive feature of these being the usually enormous 

 development of the palps which correspond to the flagra or fla- 

 bella of the crustacean limbs. These palps are so elongated 

 and jointed in the spiders that they would be taken for legs by 

 an ordinary observer, and hence spiders appear to have ten in- 

 stead of eight legs. In scorpions these maxillary palps are 

 larger than any of the other limbs, and will be described here- 

 after. The eyes of the Arachnida are, when they are present, 

 always simple and few in number eight, six, four, and two 

 being the common numbers found. They never have a multi- 

 tude of hexagonal or quadrate ocelli grouped into one organ as 

 insects have. The method of breathing is very various in the 

 class, the lowest having their juices oxygenated through the 

 skin, others having trachese like insects, while the highest have 

 what are called lungs, or, more properly, pulmonibranchiae, to 

 be described hereafter. The sexes are usually distinct, the 

 females exceeding the males in size. With the exception of the 

 Pantopoda (or Pycnogonidse), a doubtful order, allied to the 

 Crustacea, none of the Arachnida are marine in their habitat. 

 Some of the lower orders inhabit fresh water, as, for instance, the 

 little scarlet water-spider. The major part live in and breathe air. 



We will now take a common spider as the example of the 

 class, so that we may go into detail without misleading the 

 reader by the idea that the description will apply to other 

 members of the class. 



The cephalo-thorax is a somewhat flattened segment. Its 

 integument is of a harder consistence than that of the abdomen. 

 The upper plate is called the shield, and the lower the breast- 

 plate or sternum. Between the edges of these two, along the 

 sides of the body, spring the legs. The shield is wider than the 

 breastplate, and overlaps it, so that while the bases of the legs 

 are well seen from below they are not seen from above. The 

 shield is usually narrower in front, and wide* and heart-shaped, 

 or rounded, behind. It is raised into a conical protuberance at 

 the fore part, and on this the eyes are set. Two lines of depres- 

 sion run on each side of the cone, and from these other lines run 

 off to the spaces between the legs, while a marked dent is often 

 seen at the middle of the hind part. The breastplate is often 

 rounded, or heart-shaped, with the apex backward, or in the 

 form of an escutcheon. The box of the cephalo-thorax contains 

 the stomach, main nervous masses, and the muscles of the limbs. 

 The eyes in the common spider are eight in number, in two 

 transverse lines of four each. They are, however, in the various 

 species very differently situated, and of different relative size. 

 Their relative position, number (two, six, or eight), and size are 

 much depended on to distinguish the genera. Sometimes they 

 are mounted on a pyramid, or elevated watch-tower, which risea 

 from the shield in a very grotesque manner. The mandibles 

 spring from under the truncated front of the shield, and are 

 directed downwards. They are of two joints, the thick descend- 

 ing basal joint having attached to the outer part of its end a 

 hooked claw, which works on a joint, so that the point of it can 

 play from the side towards its fellow on the other side. When 

 the claw is completely flexed, it lies in a groove 'which runs 

 along the far edge of the rear joint. This groove has its two 

 walls generally armed with points or teeth. The maxillae, or 

 under-jaws, consist of two plates, the inner edges of which are 

 in motion approximated or removed from one another. Their 

 edges and upper surfaces are often studded with small spines. 

 From the base and outside of these plates arise the long-jointed 

 palps, which in the female end in claws like the legs. In the 

 male a very complex organ is found, which can be doubled up 

 into a rounded fist, by which the adult male can be readily dis- 

 tinguished from the female. The lower lip, or labrum, is of 

 various shapes, but usually quadrate. The legs are seven- 

 jointed. The first joint is called the coxa, or haunch ; the 

 second, the trochanter ; the third, the femur. These last two 

 form the thigh, and to this point the legs are like those of in- 

 sects. The tibia, or shank, which is whole in the insect, is in 

 spiders of two pieces ; while the foot, instead of being in five 

 small bead-like joints, is of two pieces only, and they are of the 

 same thickness as the joints which precede them. The last 

 joint has two, three, or more movable curved claws which are 

 often toothed like a comb. On the under-side of both joints 

 there are sometimes found pads, hairs, or spines, which can 

 be opposed to the claws, and so form an effective hand for 

 weaving. 



The abdomen is a globular or oval bag. It often overhangs 

 the thorax in front. Its walls are very flexible and elastic, as 

 is necessary, in that at certain seasons it is distended with eggs. 

 It contains the major part of the fat and liver masses, the organs 

 of generation, and the web-secreting glands. It is attached to 

 the front segment by a very narrow stalk. Through this thin 

 stalk, however, prolongations of almost all the organs of the 

 body are carried. Thus the alimentary canal and the small 

 hinder continuation of the nervous cord pass from the cephalo- 

 thorax to the abdomen, and the blood-system is continued for- 

 ward from the latter to the former. If the spider be placed on 

 its back, two plates, with a slit on the inner side of each of 

 them, will be seen. These plates cover the breathing cavities, 

 or pulmonibranchiae, as they and their contents are called. Be- 

 tween them is the opening of the generative organs. The anus 

 is at the extreme end of the abdomen, and immediately below 

 it are the palp-like jointed protuberances through which the silk 

 of the web is forced or drawn. These are in three or four pairs, 

 and they are perforated at the ends with many small pores, to 

 the number estimated at 1,000. We trust the reader has 

 now a pretty clear idea of the outer form of the spider ; and he 

 cannot do better than verify the description by catching a spider, 



