No. 34-] HEMIPTERA OF CONNECTICUT I HETEROPTERA. 383 



Suborder Heteroptera. 



Key to Families* 



1. Antennae shorter than the head, generally concealed in cavities 



between head and thorax ; metasternal orifices absent 2 



Antennae as long as or longer than the head, exposed 8 



2. Ocelli present; littoral species; not over 10 mm. in length 3 



Ocelli absent ; aquatic species 4 



3. Antennae exposed ; front legs similar to intermediate 



OCHTERIDAE, p. 391 



Antennae concealed; front legs raptorial NERTHRIDAE or 



GELASTOCORIDAE, p. 392 



4. Hind tarsi without two distinct claws (except Plea which is less 



than 3mm. in length); front legs not raptorial in structure; 



moderate or small in size 5 



Hind tarsi with claws ; front legs raptorial 6 



5. Head overlapping thorax dorsally ; body flattened above 



CORIXIDAE, p. 386 



Head inserted in thorax ; body convex above 



NOTONECTIDAE, p. 404 



6. Membrane reticulately veined ; large in size 7 



Membrane without veins; moderate in size . .NAUCORIDAE, p. 402 



7. Apical appendages of abdomen long and slender, not retractile; 



hind legs not flattened NEPID AE, p. 399 



Apical appendages of abdomen short and flat, retractile; hind 

 legs distinctly flattened, natatorial . . .BELOSTOMATIDAE, p. 396 



8. Head shorter than thorax including scutellum 9 



Head as long as entire thorax, both elongated; body and 



appendages slender ; aquatic, length about 11 mm 



HYDROMETRIDAE, p. 663 



9. Claws of at least the front tarsi distinctly anteapical with terminal 



tarsal segment more or less cleft; aquatic, living on the surface 10 

 Claws all apical, last tarsal segment entire; aquatic and terrestrial 

 forms 11 



10. Hind femora extending much beyond apex of abdomen ; inter- 



mediate and hind pairs of legs approximated, very distant from 

 front pair; ocelli present, but sometimes very obscure; moderate 



in size GERRID AE, p. 658 



Hind femora not extending much beyond apex of abdomen ; inter- 

 mediate pair of legs about equidistant from front and hind pairs 

 (except in Rhagovelia) ; ocelli obsolete or absent; moderate to 

 minute in size VELIIDAE, p. 416 



11. Antennae five-segmented 12 



Antennae four-segmented, disregarding minute ring segments; 



(antenniferous tubercles of head should not be mistaken for 

 segments, figs. 166, 167 and 169) 13 



12. First and second segments of antennae thicker than the others ; 



minute in size NAEOGEIDAE or HEBRIDAE, p. 675 



First segment of the antennae thickened, second slender; margin 

 of head carinate above insertion of antennae; moderate in size, 

 rarely minute . 3 2 



* Arranged by Dr. H. M. Parshley. 



