80 Key to Families of North American Insects. 



32. Fourth dorsal segment of abdomen constricted medially; gland openings of 



metathorax usually obsolete, if rarely visible placed between the hind coxal 

 cavities and emitting two divergent grooves. (Corizus, Harm6stes) (PL 



14, fig. 331) CORIZHXS 



Basal margin of fourth and fifth dorsal segments usually sinuate in parallel 

 manner; gland openings of metathorax almost always distinct 33 



33. Head much narrower and shorter than the prothorax, cheeks usually reaching 



behind insertion of antennae; exterior margin of hind coxal cavities nearly 

 parallel with axis of body. (Anasa [A. tristis, Squash-bug], Leptoglossus 

 [L. phyllopus, leaf-footed Bug], Lept6coris [L. tritittatus, Box -elder plant- 

 bug]) (PL 13, figs. 317, 318, 320; PL 14, figs. 334, 341) COREDXE 



Head nearly as broad and long as prothorax, cheeks scarcely extending behind 

 base of antennae; exterior margin of hind coxal cavities more or less trans- 

 verse. (Alydus, Stachyocnemus.) ALYDEhE 



84. Anterior lobes of the head produced at the apex; membrane of the fully winged 



forms usually with four free veins and coriaceous at the base; tarsi two- 

 jointed. (Piesma.) PIESMID^ 



Anterior lobes of the head not produced; membrane of the fully winged forms 

 entirely membranous; tarsi three-jointed 35 



85. Antennse not elbowed; head not constricted in front of the eyes. (Blissus 



[B. leucopterus, Chinch-bug], Oncopeltus, Geocoris) (PL 14, fig. 343). 



(LYGJE1DM} MYODOCHIDjE 



Antennse elbowed, the first joint long and clubbed, the last joint spindle-shaped; 

 head constricted in front of the eyes; scutellum small; femora clubbed. 



Stilt Bugs. (Jfilysus, Neides.) (BERYTIDM) NEIDnXE 



36. Scutellum narrowed behind, rarely almost covering the abdomen; veins of 

 membrane arising near inner basal angle from a vein extending from this 

 angle nearly parallel with the margin of the corium. Stink bugs. (Cos- 

 mopepla, Euschistus, Murgantia [AI. histrionica, Harlequin Cabbage-bug], 

 Peribalus, Brochymena.) (PL 13, fig. 314; PL 14, fig. 332.) 



PENTATOMIIXE 



Scutellum very convex and large, nearly or quite covering the abdomen; mem- 

 brane with a curved or oblique crossvein whose inner end extends away 

 from the corium; hind wings with a heavy abrupt spur-like vein (hamus) 37 

 87. Corium narrow, and pointed; tibiae strongly spinose; (Thyreocoris (=Con- 

 m/<pna),Cydnus) (CORIMELMNID,CYDNlDfi). . THYREOCORIIXE 

 Corium broad, obtuse at apex; tibiae smooth or with small spinules. (Eury- 

 gaster.Homaemus.) SCUTELLERID^ 



CLASS THYSANURA. 



Rather small, wingless, terrestrial insects of active habits; 

 body generally clothed with scales; antennae hair-like, many- 

 jointed; abdomen composed of eleven segments, the last furnished 

 with a pair of long, filiform many-jointed cerci and usually with 



