130 THOMAS SAY FOUNDATION 
PLATE 3 
FIGURES 33-49 
33-38 Perla hastata Banks 
Note the epipharynx on the labrum; the sharp tooth mandibles 
without molar, the small glossae and the large paraglossae, each 
terminating in a spinulose papilla; the slender galea, the bidentate 
lacinia, and the long cardo and stipes. 
39-43 Isogenus colubrinus Hagen 
Mouth parts very similar to those of above species 
44-49 Perlodes tibialis Banks 
The mouth parts of this species are very similar to those of the 
previous species but the galea is distinctly two-segmented, and the 
lacinia is quite wide at the base of the terminal teeth. 
