102 ox SOME COMMON SPECIES 



Regarding the food of Uropoda vegetans, I have not yet been 

 able to come to any conclusion. I have never seen them feeding, 

 and they crawl about with extreme slowness. Hitherto, I have 

 only found them when attached to various beetles, to Porcellio 

 scaber, one of the wood-lice, and on two occasions — one of which 

 is here shown (Fig. 7) — to the dorsal plate of a Gamasus. Their 

 manner of attaching themselves is peculiar. The Gamasi 

 {Coleoptnitonim) can run with perfect ease over the smoothest 

 glass, attaching themselves by the suckers at the end of the feet ; 

 in addition to which their very powerful chelate mandibles would 

 enable them to grasp the hairs with which most insects are more 

 or less provided, and even should their unwilling host shake them 

 off, they are so extremely active that they could jump on again in 

 an instant, and well merit the name of Celeripes, which was given 

 by Montagu to the genus Pteroptus, and which deserves it far less. 



The nymphs of Uropoda, on the other hand, are slow in all 

 their movements, their legs being comparatively short, and gene- 

 rally kept doubled up and fitting into grooves on the under-side of 

 the body, and their suckers seem less eftective than those of 

 Gamasus ; the pincers at the end of their mandibles seem also less 

 fitted for a firm grasp. Accordingly, they " drop anchor," so to 

 speak, where they wish to remain. They exude, either from the 

 anus itself or close to it, a whitish, transparent, gummy substance, 

 which becomes quite hard, but retains its elasticity, and which 

 forms a cord by which they remain firmly attached, as shown in 

 Fig. 7. It was on account of this habit that De Geer gave them 

 the name " Uropoda " : ovpa — a tail, ttovq — a foot ; and " 7'ege- 

 tans^' because they seemed to grow like a flower on its peduncle, 

 and because he believed that this cord was a tube through which 

 the mite obtained nourishment from the insect to which it had 

 attached itself, and he said that when they moved they detached 

 the end of the cord from the beetle or other insect. In this, 

 however, he was mistaken, as it is the end next the body of the 

 parasite which is let go. On a specimen of Porcellio scaber,^ I 

 have several of the cords still remaining, from which the Uropoda 

 have detached themselves. It was Duges who first found out its 



* This i.s, I ihink, a different sjjecics to that fuuml on the beetle. 



