1 82 AN INTRODUCTION TO ENTOMOLOGY. 



TABLE FOR DETERMINING THE FAMILIES OF HETEROPTERA. 



A. Antennae short, and nearly or quite concealed beneath the head. 



B. Ocelli wanting; insects aquatic, and, excepting Nepidae and Naucoridae, 

 with legs fitted for swimming. 



C. Head overlapping the prothorax ; fore tarsi flattened, consisting of one 

 segment, and ciliated. Fam. XL— Corisidae. 



CC. Head inserted in the prothorax ; fore tarsi normal. 



D. Body thick, dorsal aspect of abdomen very convex. Insects which 



swim upon their back. Fam. XII.— NotoneCTID^e. 



DD. Body either flat or elliptical in outline, or much elongated; caudal 



end of abdomen furnished with a respiratory tube composed of a 



pair of grooved filaments. Fam. XIII. — NEPID/E. 



DDD. Body flat, oval or ovate, without respiratory filaments. 



E. Abdomen with a pair of strap-like caudal appendages (these ap- 

 pendages ate retractile, and are frequently withdrawn from sight); 

 legs flattened for swimming. Fam. XIV. — Belostomatid^E. 



EE. Abdomen without caudal appendages; legs fitted for crawling 

 rather than swimming. Fam. XV. — Naucoridae. 



BB. Two ocelli present ; insects aerial, although living near the water ; body- 

 short and broad ; eyes very prominent. Fam. XVI. — Galgulidae. 

 AA. Antennae prominent, free, rarely (Phymatidae) fitting in a groove under 

 the lateral margin of the pronotum. 

 B. Body linear ; head as long as the three thoracic segments. 



Fam. XX. — Limnobatidae. 

 BB. Body of various forms, but, when linear, with head shorter than the 

 thorax. 



C. Distal segment of the tarsi more or less bifid, with the claws inserted 

 before the apex. 



D. Body usually elongated, prothorax narrow ; rostrum 4-jointed ; 

 second and third pairs of legs extremely long and slender. 



Fam. XIX. — Hydrobatid^e. 

 DD. Body usually stout, oval, and broadest across the prothorax; ros- 

 trum 3-jointed ; legs not extremely long. Fam. XVIII. — Veliad/E. 

 CC. Distal segment of the tarsi entire; claws inserted at the end. 

 D. Antennae 4-jointed.* 



E. Wing-covers reticulated, and of one uniform thin substance 

 throughout ; very rarely (Piesma) with a distinction between the 

 corium and membrane. Fam. XXVI. — Tingitid.e. 



EE. Wing-covers of various forms or absent, but not of the form pre- 

 sented by the Tingitidae. See Fig. 171. 

 F. Rostrum 3-jointed. 

 G. Ocelli wanting. 



H. Wing-covers rudimentary, with only corium (Acanthiin^. 



Fam. XXVII. — Acanthiid.e. 



* In certain families there are minute intermediate joints between the principal joints 

 of the antennae. For the purposes of this table these intermediate joints are not counted. 



