492 Mr. Buackwatt on the Pulvilli of Insects. 
side with numerous cup-shaped suckers of various sizes, which 
have their edges (the larger ones atleast) 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, 
Dyticus 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, 
ditfer from them essentially both in structure and function. 
XXVII. 4n 
ME LL Ld Ud Lu riu al 
re eect OE iem MAD Mat et ns 
