HARDWICKE'S SCIENCE-GOSSIP. 



i59 



walls of the 2nd segment. By their contraction they 

 expand the process in a contrary direction. The 

 posterior limbs are furnished only with retractor 

 muscles, the circle of hooks they carry being usually 

 expanded. These muscles are inserted in the anterior 

 ventral walls of the 12th segment and to the anterior 

 •dorsal walls of the same. The latter cross each other. 

 The terminal bristle-bearing papillae are each 

 furnished with a muscle inserted in the anterior dorsal 

 wall of the 12th segment. (Fig. 65.) 



The Nymph. 



For how long a time the larva exists as such I do 

 ■not know, but it builds for itself small cases of mud 

 in which it dwells attached to the side of the tank, 

 or forms tunnels in the sediment at the bottom. 

 Occasionally they may be seen swimming with a 

 quick often-repeated series of jerks, forming their 

 body into a shape resembling the figure 8. The final 

 •larval coat is shed, and the nymph form assumed 

 beneath the water at the bottom of the tank. The 

 larva leaves its tunnel and crawls above the mud 

 previous to this change. 



The form of the nymph is very different to that of the 

 larva. The mouth appendages undergo much change 

 — two large compound eyes replace the four smaller 

 ones. The anterior hooked limbs dis- 

 appear, and to each of the three first seg- 

 ments — now united to form the thorax — a 

 pair of many-jointed limbs is attached, to 

 the 2nd, dorsally, a pair of wings and 

 similarly to the next, a pair of halteres. 

 The head is bent down upon the thorax, 

 and the wings and limbs lie closely against 

 it. The segments of the abdomen suffer 

 less change, the limbs of the nth and 12th 

 are gone, and in their place the terminal 

 segment supports posteriorly a divided 

 •semi-circular appendage bearing respira- Fjg- 68. 



tory hairs. Respiration is effected by Fig! 70. 



coming forth is a more tedious performance, and with 

 their wings yet within the old case, they fall back into 

 the water, where they lie until their struggles have 

 liberated their imprisoned members (Fig. 66). 



The Imago. 



I have given figures of the male and female Tipula 

 plumosa, Linn. The lessen figures are natural size. 

 The male is distinguished from the female, by his 

 antenna;, abundantly feathered, rising from two large, 

 globose, black prominences between the eyes ; the 

 terminal segment of his abdomen carries posteriorly, 

 besides the two pulps, common to both sexes, a pair of 

 claspers. The female possesses two fine antennre which 

 rise from two lesser prominences, similarly situated. 

 They bear but few hairs, hardly perceptible. The 

 terminal segment of her abdomen bears on its sternal 

 surface two palpi, prolonged backwards, they are 

 larger than those possessed by the male (Fig. 67). — 



Llandudno. 



A SriDER'S DEADLY FOE. 



I SEND herewith drawings and notes of an ich- 

 neumon wasp that preys upon a small spider in 

 Ceylon. I have been unable to identify the insect, 



Fig. 6S 



1 ~^\.i^ 



^•wmS 



4 



Fig. 71. 



.branchke, shining silky hairs rising in three 

 it ufts from each side the thorax above the 

 head, and others from the terminal segment 

 of the abdomen. I believe that for the greater part 

 of the time the nymph remains beneath the sediment 

 .at the bottom of the tank, but before the final change 

 it comes forth, and with much apparent effort swims 

 •to the surface. Here it rests for a short time, the 

 dorsal plate of the thorax at the surface, the abdomen 

 •bent beneath the water. In a few minutes it bends and 

 straightens itself repeatedly. These movements occur 

 several times with short rests between. In less than a 

 quarter of an hour after it has risen to the surface, the 

 thorax splits down the dorsal plate and the head of 

 the imago projects. I have seen them rise straight 

 up as though they had received a mechanical impetus, 

 they ascend so smoothly from the old nymph skin, 

 taking flight immediately they are free. Usually this 



Spider, with parasite in situ, magnified. 



■Spider, natural size. 

 — Parasite, further magnified, showing eight retractile tubercles 

 he back, each of which is crowned with numerous minute fleshy 



upon t 

 hooks. 

 Fig. 71. — A single tubercle, highly magnified. 



but it is possibly allied to the " pimpia " mentioned 

 by Packard as being parasitic upon a spider in 

 Europe ("Guide to Study of Insects," p. 193). 

 The spider usually attacked is a small black animal 

 with globose abdomen, that spins a loose irregular 

 web on the under-surface of leaves. The ichneumon 

 wasp appears to oviposit upon female spiders only, 

 the males being much smaller and unable to support 

 the wasp grub. The egg is fixed to the abdomen of 

 the spider close to its junction with the cephalo- 

 thorax. The newly -hatched larva immediately 

 pierces the skin and commences to absorb the 

 juices of its host. The spider continues to feed 

 and remains apparently in good health until the 

 parasite is full grown, when the latter destroys 



