SOME INSECT ADAPTATIONS. 87 
even able to feather as they row along, yet here, as 
elsewhere, the plan of structure is the same as that 
’ 
Fic. 80.—Fore Legs of a Water-bug. 2, open; A, closed; C, enlarged 
to show sheath. 
seen in the cockroach and grasshopper. Some butter- 
flies of strong flight use their legs so little that their 
front legs are mere threads, yet they retain the marks 
Fic. 81.—Legs of Dyticus. A, hind legs for swimming; JB, fore leg 
with suckers. 
of the same plan we have found in the other insects 
examined. 
What is true of the legs is also true of other impor- 
