240 



partly visible. The mandibles are fonned for gnawing soft vegetable matter, being 

 broad and amied with three teeih, which are not curved nor very sharp. 



Genus. — Julus. 

 Each seo-ment has but one pair of legs ; the segments are alternately scaly and 

 membranaceous, the latter being covered by the former. The clypeus has the situa- 

 tion of the labrum, its border is excavated and tridentate. The mandibles have three 

 or four short obtuse teeth. There are two pair of maxillas, one pair narrow, soldered 

 together, and fonning the labium of insects ; the other pair, or the maxillae of insects, 

 are joined to the first pair, and with them form the labium of this genus. There are 

 no palpi. The first pair of legs has the coxae approximate and soldered together, the 

 thighs have but one joint, the tibiae have two joints, the tarsi are pointed and have no 

 distinct claw. In the second pair of legs the coxae are elevated parallel to each other, 

 and are also soldered together, but the thighs have two joints, and a distinct claw ter- 

 minates the tarsus. In the third pair of legs the coxae are distinct, and though ap- 

 proximate at their base they diverge from each other toward their tips. These three 

 pair increase progressively in size, and at the same time are so modified that the third 

 in no wise differs from the following legs. 



Julus pulchellus. This is by far the most abundant species near London, where it 

 may be found during most part of the year in gardens, at the roots of vegetables, to 

 which it does much mischief. It feeds on the roots of potatoes, carrots, turnips, ra- 

 dishes, onions, cabbages, cauliflowers, parsley, Jerusalem artichokes, beans &c. ; it 

 also attacks hyacinth-bulbs, and feeds on apples and other fruit when much decayed, 

 and I have seen it in clusters, devouring a large dead worm. It is an elegant crea- 

 ture in form and motion as well as in colour ; it is white and almost transparent, like 

 glass, and has a row of crimson spots on either side, along the whole length of the 

 body, the head and tail excepted. When very young it is quite white, next a crimson 

 spot appears on either side, and it successively acquires more and more, till most of 

 the segments are thus adorned. The following is a list of the variations that I have 

 observed in the number of these spots on one flank of the body: — 1, 6, 7, 11, 14, 15, 

 16, 20, 21, 22, 25, 27, 28, 34, 35, 37, 39, 41, 42, 43. 



The young of Polydesmus and of Craspedosoma, Julus pusillus and a small spe- 

 cies of Lombricus, a little silver-hued Smynthurus, and the white, yellow and orange 

 offspring of Porcellio and Araaadillo, are companions to this species in the injuries it 

 inflicts on vegetables, so also are some minute species of Staphylinites, such as Oxy- 

 telus, and their larvae. When its head or antennae are touched it is very sensitive, 

 and turning on its side, curls its body into the form of an Ionic volute, or of a Pla- 

 norbis or Ammonite shell, that is, into a succession of circles, one outside another, and 

 of which its head forms the common centre. It shows that it dislikes being breathed 

 on, by curling round its head and twisting its body like a worm. Having lost the 

 hinder part of its body it crawled as quickly as before, but its movements were irregu- 

 lar and unsteady, and it frequently turned round its head as if to look behind it. The 

 crimson spots are situated under and around a series of pores on each side of the body, 

 which are called " foramina repugnatoria," for through them is emitted a volatile oil, 

 by which the insect defends itself. The crimson colouring matter is comprised in 

 this oil, which soon flies off, leaving the colour behind, which assumes, either imme- 

 diately or in a few days, a violet-black hue, and that this change is occasioned by the 



