March 1, 1S68.] 



HARDWICKE'S SCIENCE-GOSSIP. 



51 



under consideration. These are Tetranychus ulmi, 

 Koch, and Tetranychus lintearius, Dufour. The 

 former is described and figured by Koch (Deutsch- 

 lands Crust. 1, 11.) A figure is also given in 

 bciENCE-Gossip for 1S67, p. 120. The latter is 

 described and figured by Dufour (Ann. Sc. Nat., 1st 

 ser., xxv., 2S1, PI. ii., 4, 5), and also described by 

 Walekemier (Apt., p. 167). Tetranychus ulmi 

 agrees tolerably well with the present species as 

 regards its colouring ; though the head, thorax, and 

 legs are much too pink (rosenroth. Koch). Of 

 Tetranychus liutearius, I have had no opportunity 

 of seeing a figure ; and certainly the description is 

 brief enough to have satisfied Linna3us himself -. 

 " Red, legs of a lighter colour ; hairs long ; white 

 on the dorsal surface and on the legs. It lives in 

 societies on shrubs, on which it spins a delicate 

 whitish web, similar to that of the spider. Ob- 

 served at S. Sever." The above, meagre as it 

 is, agrees in many respects with our species; 

 which is of a red hue, has long white hairs on 

 its back and legs, lives in societies, and spins a 

 web. But I am afraid it would suit almost equally 

 well for more than one other of the Acari. The legs 

 of our mite, however, are not appreciably lighter in 

 colour than the body ; and in our species the dorsal 

 surface is bordered by bands of a decidedly darker 

 hue than the body itself. Moreover, in neither of 

 the species named is there the slightest allusion 

 made to the green individuals, which could hardly 

 have been passed over by such careful observers 

 as Koch and Walckeniier. Tetrauychus ulmi is too 

 far restricted in its habitat, being confined to the 

 elm. Tetranychus lintearius too diffuse, being said 

 to occur on shrubs generally ; whereas the present 

 species is, I believe, restricted to the furze or gorse. 

 As it appears that the subject of the present 

 notice is not identical with any of the continental 

 species, and that it has not yet found a place in our 

 fauna, I suggest the name of Tetranychus ulicis (the 

 Furze Mite) * as an appropriate title to distinguish 

 it from its numerous congeners. 



* Tetranychus ulicis (Furze Mite).— Body elongate-ovate* 

 dark-red, opaque ; sides lobate, marked by darker bands ; of 

 uniform colour below ; sparingly clothed above with white 

 hairs (spines?) mostly directed backwards. Legs rather 

 slender, hairy (hairs all directed forwards, terminal ones 

 incurved), seven -jointed; first and second joints short, stout ; 

 third joint longest; seventh thin, transparent, retractile, 

 terminated by four claws with a tuft of stiff, brush-like hairs 

 at their base : pulvilli wanting. Eyes two on each border of 

 the thorax, conspicuous, darker in colour than the surround- 

 ing cuticle. 



With the above are found other individuals (quere ; young, 

 or males ?) : body smaller ; abdomen shorter, rounder, of a 

 nearly uniform dark green colour; lateral margin continuous. 

 Head, thorax, and legs pink. Eyes bright clear red. 



Animals living in societies, forming a tent-shaped blueish 

 web on branches of furze {Ulex Europceus). 



Rare? Rusthall Common, Dr. Milner Barry, 1855; Budleigh 

 Salterton, Devon, Mr. J. C. White, I867. 



GOSSAMER. 



fTlHE 10th of -last November was a lovely 

 -*- autumnal day in Leicestershire. Strolling 

 out for a walk with my children, we found the 

 fields, both grass and ploughed, carpeted with a 

 shining veil of Gossamer. 



The sun was in the south-west, nearly down, and 

 all the glittering threads seemed to lie in one 

 direction — north-west and south-east. On careful 

 examination, however, by several different methods, 

 we satisfied ourselves that this was an illusion ; that 

 the threads were crossed and interlaced in a great 

 variety of directions, but that only those which lay 

 at right-angles to a line drawn from the sun to the 

 observer reflected the sun's direct rays, and that 

 only these therefore were visible at a distance. We 

 caught a number of the clever little spinners. There 

 seemed to be at least two species, one with the 

 abdomen about as large as a mustard-seed, the 

 other not more than half that size, and both rather 

 dark coloured on the upper surface. 



They would run nimbly about the baud, but did not 

 appear inclined to leave it of their own accord. A 

 slight shake, however, made them drop down several 

 inches, and hang suspended at the end of a thread. 

 It was a wonderfully calm day, and yet there w r as a 

 sufficient current of air to move these delicate 

 weathercocks, which all indicated that the direction 

 of the current was from south to north. We 

 watched them very closely, and noticed that for 

 some seconds, or even a minute or two, they would 

 wave about at the end of their thread without 

 allowing it to be lengthened; and that then, 

 suddenly, they would lengthen the thread and sail 

 away in the direction of the wind. Generally, when 

 they disappeared in this way, their flight was so 

 rapid that they seemed to vanish like a flash, leaving 

 their long streamer behind, which floated hori- 

 zontally in the light air, and always in the same 

 direction. But once, as I held and watched one of 

 the larger species, he suddenly went off at so 

 moderate a speed that I could see his little dark 

 body against the light sky until he had got three or 

 four yards away, when I lost sight of him. 



We concluded, at first, that as the spiders always 

 followed the direction of the wind, they were 

 simply blown away, having the power of resistance 

 at pleasure by checking the outflow of their thread. 

 But there is one consideration which destroys this 

 theory entirely. The velocity of a current of air, by 

 which neither the blade of grass nor the leaves of 

 trees are perceptibly moved, can scarcely be greater 

 than one or two miles an hour ; whereas the velocity 

 with which these spiders shot away was certainly 

 not less than four or five miles an hour. Plainly, 

 therefore, there must have been some other motive 

 force at work besides the air-current. What was it ? 

 Loughborough. F. T. Mott. 



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