238 THE UNIVERSITY SCIENCE BULLETIN. 
STRUCTURAL ADAPTATIONS TO FEEDING. 
External. 
The Corixids possess the most obvious adaptations of their 
limbs to definite functions of any of the water bugs. As 
early as 1833 Leon Dufour, in his “Recherches anatomiques et 
Physiologiques sur Les Hemipteres accompagnees de consid- 
erations relatives a l’histoire naturelle et a la classification 
de ces insectes,” gave a detailed description of the various 
limbs of Corixids. In 1873 Buchanan White, to whom we owe 
a great deal for a splendid series of notes regarding Corixids, 
mentioned the function of the different parts, based upon 
his person] observation. He states that the hind limbs are 
flattened and fringed for swimming, that the long, slender 
middle limbs anchor the bug to some submerged object, and 
the fore limbs are employed in food getting, though he con- 
fessed his uncertainty as to the forage gathered. 
Comstock, in his ‘Introduction to the Study of Entomology,” 
also notes the differentiation of the limbs. 
The very unique mouth parts that led Borner, 1904, to 
place them in a suborder by themselves, and for which he 
proposed the name Sandaliorrhyncha, are well adapted to 
the unusual method of feeding practiced by these insects. 
There iS no extended beak as in other bugs, yet a morpho- 
logical study of the various parts, such as those made by 
Metschniikoff, 1866, Giese, 1883, Wedde, 1885, Heymons, 1899, 
Bugnion and Popoff, Muir and Kershaw, and others indicate 
the close relationship of these with other bugs. The draw- 
ings on plate XXX show the mouth parts. The face of the 
bug is seen to be flat with the buccal opening on the front 
side rather than at the tip. Two triangular flaps, controlled 
by muscles, permit the enlargement of the orifice. The sty- 
lets are very short and stout, the outer pair blunt-tipped and ~ 
notched on their outer margins. A condition quite different 
from the pointed and retrorsely-barbed stylets of Notonecta, 
for instance. The inner pair are broad, placed one above 
the other, and rolled into semi-cylinders. Bugnion and Popoff 
say of these internal stylets of Hemiptera: “. . . The 
internal stylets forming by their juxtaposition two conduits, 
very fine, one of which ordinarily placed on the dorsal side is 
the “Canal de succion’” which is continuous from beak to 
