346 Annals of the Carnegie Museum. 



cc. Antennae much longer than the body, setaceous, deHcately tapering. 

 Stridulating organs, when present, situated on the anal field of 

 the tegmina. Auditory apparatus situated near the base of the 

 front tibiae. Ovipositor usually prolonged into a compressed 

 blade or needle, its parts compact. 

 d. Ocelli variable. Tarsi three-jointed, those of the front legs or else 

 of the hind legs differing from the others in structure. The 

 middle field of the tegmina in repose, like the anal field, nearly 

 or quite horizontal; male tegmina (when present) furnished on 

 the dorsal surface with a tympanum (very rarely absent) ex- 

 tending across both the anal and median areas, crossed by a 

 prominent nervure formed by the main anal vein, and as a 

 whole broader than the rest of the tegmen. Ovipositor (unless, 

 as rarely, concealed) forming a nearly cylindrical straight or 

 occasionally upcurved needle, the inner valves generally scarce- 

 ly exposed except at the expanded tip. .Suborder Achetoidea. 

 dd. Ocelli generally wanting. Tarsi nearly always four- jointed, very 

 similar in structure on all the legs. Middle field of tegmina in 

 repose, like the costal field, nearly or quite vertical; base of the 

 male tegmina (when present) furnished on the dorsal surface with 

 a tympanum limited to the anal area, crossed by a prominent 

 nervure formed by the last branch of the anal vein, and as a whole 

 narrower than the rest of the tegmen. Ovipositor (unless, as 

 rarely, concealed) forming a strongly compressed, generally ensi- 

 form blade, the inner valves almost alwaj's partially exposed the 

 entire length of the ovipositor, the tip not expanded. 



Suborder Tettigonoidea. 



hh. Posterior legs similar to the others, not constructed for jumping. Tarsi 



three-jointed. Organs of flight (when present) in a normal position. 



Ovipositor concealed by the subgenital plate Order Dermaptera. 



c. Always apterous. Parasitic on mammals. 



d. Eyes much reduced. Mandibles strongly flattened, not adapted to 

 mastication, but the inner margin densely clothed with bristles. 

 Cerci feebly chitinized, forming incipient forceps. Maxilla with 

 the inner lobe furnished with two apical teeth (Malayan Archi- 

 pelago) Suborder Arixenia. 



dd. Eyes absent. Mandibles normal. Cerci non-segmented, feebly 

 chitinized, not horny. Inner lobe of maxilla with four apical 



teeth. Viviparous. (African.) Suborder Hemimerina. 



cc. Fully winged or apterous. The wings, when present, four in number, 

 the anterior pair corneous, the hind pair membranous, complicately 

 folded and tucked beneath the former. Not parasitic. Cerci modified 

 into strongly chitinized horny forceps. Inner lobe of the maxilla 

 provided with four apical teeth. Oviparous. . . Suborder Forficulina. 



Key for Separating the South American Families of Achetoidea. 



A. Tarsi compressed, the second joint minute. 

 h. Posterior tibiae moderately robust. 



