Mr. Blackwall on the Fulvilli of hisects. 491 



asserts, though when placed in such a situation relative to the 

 eye of the observer that the hairs connected with them are fore- 

 shortened, they certainly present an appearance which, on a 

 superficial view, might lead to the latter conclusion. If the 

 slender bristles on the inferior surface of the pulvilli of some of 

 the larger Coleoptera, Prionus cervicornis for example, be very 

 highly magnified, each, beside the numerous short hairs which 

 project from its sides, will be found to have a small dense brush 

 of exceedingly minute hairs at its extremity; and as the hairs 

 on the pulvilli of flies, and many other insects belonging to 

 various orders and genera, with which I have experimented, 

 perform a function similar to that exercised by the bristles, and 

 also exhibit a striking resemblance to them in external appear- 

 ance, it is extremely probable that they are analogous in struc- 

 ture ; though from the smallness of their dimensions, I have not 

 yet been able to satisfy myself that this is the case by direct 

 observation, notwithstanding I have employed the highest mag- 

 nifying power at my command. The hold which insects are 

 enabled to take of any roughness or irregularity of surface by 

 means of the fine hairs composing the brushes must be very 

 considerable; and whoever examines the most carefully polished 

 glass in a favourable light with a powerful lens, will speedily be 

 convinced that it is not free from flaws and imperfections. 



That some species of spiders can support themselves against 

 gravity on the sides of polished bodies by the assistance of a 

 mechanical apparatus similar in principle to that employed by 

 insects in like circumstances, I have announced in a communi- 

 cation recently made to the Linnean Society * ; and the fact 

 affords a strong collateral proof of the truth of my theory. 



I am aware that the males of several aquatic beetles have the 

 tarsi of the first and second pair of legs supplied on the under- 



* See preceding paper, " On the Structure and Economy of Spiders." 



side 



