126 
THE STUD Y OF INSECTS. 
BB. Hind-tarsi with two claws. 
C. Caudal end of the abdomen furnished with a respiratory tube 
composed of a pair of grooved, thread-like organs, p. 130. 
NEPIDjE. 
CC. Caudal end of abdomen without respiratory tube. 
D. Legs flattened, fitted for swimming ; caudal end of the ab¬ 
domen furnished with a pair of strap-like appendages (these 
appendages are retractile and are frequently withdrawn from 
sight), p. 131. Belostomidje. 
DD. Legs fitted for walking; abdomen without strap-like 
caudal appendages. 
E. Without ocelli, p. 133 . Naucorid«<e. 
EE. Ocelli present, p. 133. Galgulidje. 
AA. Antennae at least as long as the head, usually free, rarely (Phy~ 
matidcB ) fitting in a groove under the lateral margin of the pro- 
notum. 
B. Body linear; head as long as the three thoracic segments. 
p. 136. LlMNOBATIDiE. 
BB. Body of various forms, but, when linear, with the head shorter 
than the thorax. 
C. Last segment of the tarsi more or less split, and with the 
claws inserted before the apex. 
D. Body usually elongated; prothorax narrow; beak four- 
jointed ; second and third pairs of legs extremely long and 
slender, p. 135. Hydrobatid.®. 
DD. Body usually stout, oval, and broadest across the protho¬ 
rax; beak three-jointed; legs not extremely long. p. 134. 
VELIIDvE. 
CC. Last segment of the tarsi entire, and with the claws inserted 
at the apex. 
D. Antennae four-jointed.* 
E. Wing-covers resembling network, and very rarely (Piesma 
with any distinction between the corium and the mem¬ 
brane. p. I39. . TlNGITIDiE. 
EE. Wing-covers of various forms or absent, but not of the 
form presented by the Tingitidae. See Fig. 165. 
F. Beak three-jointed. 
^In certain families there are minute intermediate segments between the 
principal segments of the antennae. For the purposes of this table these 
intermediate segments are not counted. 
