Chapter XX. 



Animal Gjills,* produced by Breeze-Flies, and Snail-Beetles. 



The structures which we have hitherto noticed have 

 all been formed of inanimate materials, or at the 

 most of growing vegetables; but those to which we 

 shall now advert are actually composed of the flesh 

 of living animals, and seem to be somewhat akin to 

 the galls already described, as formed upon the 

 shoots and leaves of plants. These were first inves- 

 tigated by the accurate Vallisnieri, and subsequently 

 by Reaumur, De Geer, and Linnaeus; but the best 

 account which has hitherto been given of them is by 

 our countryman Mr Bracey Clark, who differs essen- 

 tially from his predecessors as to the mode in which 

 the eggs are deposited. As in consequence of the ex- 

 treme difficulty, if not the impossibility, of personal 

 observation, it is no easy matter to decide between the 

 conflicting opinions, we shall give such of the state- 

 ments as appear most plausible. 



The mother breeze-fly [Oesfrics bovis, Clark; — 

 Hyjjoderma hovis, Latr.), which produces the tu- 

 mours in cattle called wurhles, or wormuls {quasi, 

 ivorm-holts), is a two-winged insect, smaller, but 

 similar in appearance and colour to the carder-bee 

 (p. 64), with two black bands, one crossing the 

 shoulders and the other the abdomen, the rest being 



* In order to prevent ambiguity, it is necessary to remark 

 that the excrescences thus called must not be confounded with 

 the true galls, which are occasionally found in the gall bladder, 

 VOL. IV. 34* 



