334 PROCEEDINGS OF THE NATIONAL MUSEUM vol. us 



metathoracic wings, and general habitus (pis. 11, 12). These di- 

 morphic differences and the structural characters used in classification 

 are semidiagrammatically drawn with their respective names attached 

 in the illustrations (pi. 1). 



The American species of Acalypta are primarily muscicolous, 

 but the host preference for the different kinds of mosses is unknown. 

 Host label affixed to pins reads simply "moss," "mosses," or 

 "sphagnum." Under unfavorable biotic conditions for mosses, 

 nymphs and adults will seek less acceptable plants nearby for feeding 

 purposes. For example, A. harheri was found feeding in numbers 

 (nymphs and adults) on hops at Coburg, Oreg., August 26, 1935, by 

 N. P. Larson. Very httle is known about the biology of the American 

 species. 



Key to Brachypterous Forms of American Acalypta 



1. Pronotum unicarinate (pis. 1-6) 2 



Pronotum tricarinate (pis. 7-14) 4 



2. Hypocostal lamina uniseriate (pi. 5) A. inniophila 



Hypocostal lamina biseriate in basal third to half, thence posteriorly uni- 

 seriate 3 



3. Paranotum mostly triseriate; discoidal area obtusely rounded at apex; bound- 



ary vein separating discoidal and sutural areas elevated and strongly sinuate 



(pi. 3) A. duryi 



Paranotum usually biseriate, sometimes with one or two intercalated areolae 

 in front; discoidal area acutely rounded at apex; boundary vein separating 

 discoidal and subcostal areas less elevated, nearly straight in basal two- 

 thirds, then apically gently curved inward (pi. 4) A. saundersi 



4. Form distinctly oblong; antennal processes spiniform, divergent, not excavated 



within (pi. 7) A. cooleyi 



Form ovate or obovate; antennal processes short, stout, blunt, excavated 

 within (pis. 8-15) 5 



5. Discoidal area about three-fifths as long as an elytron, much narrower than 



subcostal area; areolae of paranotum and costal area very large (pi. 8). 



A. thomsonii 



Discoidal longer, at least two-thirds as long as an elytron; areolae smaller 



(pis. 9-15) 6 



6. Pronotal carinae low, little raised, each composed of one row of very small 



areolae; costal area also very narrow, composed of one row of very small 



areolae (pi. 9) A. nyctalis 



Pronotal carinae more foliaceous, each composed of one row of quadrate 

 areolae; costal area wider, composed of one row of quadrate areolae . . . .7 



7. Lateral carinae of pronotum divergent posteriorly (pis. 11, 13) 8 



Lateral carinae of pronotum parallel (pis. 14, 15) 9 



8. Paranotum with front and outer margins jointly rounded, not angulate at 



anterolateral corner; discoidal area deeply concavely impressed longitudi- 

 nally, about three-fourths as long as elytron (pi. 13) A. lillianis 



Pronotum with outer margin nearly straight, not rounded but distinctly 

 angulate at anterolateral corner, discoidal area about two-thirds as long as 

 elytron (pi. 11) A. barberi 



