492 Mr. Blackwall on the Pulvilli of Insects. 



side with numerous cup-shaped suckers of various sizes, which 

 have their edges (the larger ones at least) beautifully fringed 

 with delicate hairs. These suckers, which probably serve to 

 facilitate the intercourse of the sexes, are remarkably conspi- 

 cuous on the tarsi of the males of a very common species, 

 Di/ticus marginalis, and unquestionably give them a firm hold 

 of smooth objects occurring in water, a liquid whose specific 

 gravity rather exceeds their own ; but that they are inadequate 

 to the support of this insect, the average weight of which is 

 about twenty-eight grains, on the vertical sides of dry, polished 

 bodies, in so rare a medium as air, I have had frequent oppor- 

 tunities of remarking. My chief object in adverting to these 

 singular organs on the present occasion, is to guard entomolo- 

 gists against the error of supposing that they correspond to 

 the pulvilli of insects, which, as I have endeavoured to show, 

 differ from them essentially both in structure and function. 



XXVIII. An 



