378 PROCEEDESTGS OF THE NATIONAL MUSEUM vol. 117 



Description. — Elongate oval, very strongly convex, metallic green- 

 ish or bluish, sometimes Avith head, pronotum and scutellum dull to 

 bright red, strongly shining. Head of male with two prominent, 

 cylindrical erect horns directly between eyes, a broad, deep, smooth, 

 sparsely punctulate depression behind and between them; epistomal 

 margin with two prominent, acutely pointed tubercles, entire head 

 surface minutely and sparsely punctulate ; female lacking both frontal 

 horns and epistomal tubercles, entire head coarsely and densely 

 punctured; clypeus convex and distinct in both sexes; eyes large and 

 prominent, deeply emarginate anteriorly; mouthparts reddish, max- 

 illary palpi narrowly elongate oval; basal three or four antennal 

 segments paler than remaining ones. Pronotum shghtly less than 

 twice as broad as long, sides broadly and angulately rounded, widest 

 just behind middle, marginal bead fine, sharply reflected, basal and 

 apical angles obtusely and broadly rounded, surface coarsely and 

 rather sparsely punctured, punctures gradually larger from disc to 

 lateral areas. Elytra with sides nearly parallel, narrowly margined 

 with bead strongly reflected, striae feebly or not at all impressed, 

 rather coarsely and deeply punctured, intervals flat or subconvex, 

 finely and sparsely punctate. Ventral surface of pronotum convex, 

 coarsely and densely, sometimes rugosely punctured; prosternal proc- 

 ess strongly convex, its apex truncate between coxae, not prolonged 

 toward mesosternum ; entire ventral surface more or less coarsely and 

 densely punctured; abdominal and metasternal setae, if present, 

 short and inconspicuous; epipleura abruptly abbreviated anterior to 

 apices of elytra. Male aedeagus with apical sclerite broader than 

 long (pi. 6, fig. 61). Measurements: length 2.7-4.8 mm.; width 1.4- 

 2.4 mm; 



Remarks. — This is the only shining metallic species of Neomida 

 occurring in North America. Its nearest relative appears to be A^. 

 aeneipennis, which is unknown north of the Rio Grande. Differences 

 between these two are summarized under the description of the 

 latter species. 



The most striking variation exhibited by A^. bicornis is in the 

 coloration of the pronotum, in some specimens being metallic green 

 as on the elytra and in others a brilliant red. It was to the latter 

 phase that Fabricius gave the name viridipennis, which has remained 

 unchallenged until now. 



The first suspicion that one species with two distinct color phases 

 is involved occurred when a large series containing both phases in 

 addition to several specimens of intermediate coloration (i.e., brown- 

 ish to brownish-red pronotum) were reared from a single fungus 

 taken near Newark, Del., in 1953. Since then, more than 3000 

 specimens have been studied and records kept of the pronotal color- 



