224 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



Genus AMERSIBIA Forster. 

 Alloplasta Forster. 



This genus may be readily differentiated from Meniscus by having 

 the fronds normal, flat or evenly convex and the angulate nervellus, 

 which is broken at or below the middle. 



AMERSIBIA PRIONOXYSTI, new species. 



This species is readily differentiated from all other North American 

 species described in this group by its size and color. 



Female. — Length 19 mm.; length of ovipositor 17 mm. Clypeus 

 shining with widely scattered distinct punctures; face opaque with 

 rather close, distinct punctures; immediately below the antennae is 

 a triangularly-shaped raised tubercle, the top of which is subcarinate; 

 head above the antennae opaque, finely granular, but in addition to 

 the granulation are distinct separate punctures; postocellar hne 

 slightly longer than the ocellocular line; third antennal joint one- 

 fourth longer than the fourth; mesoscutum and scutellum shining 

 with sparse, well-defined punctures; mesepisternum similarly sculp- 

 tured, except at the posterior subdorsal region there is a glabrous spot; 

 sides of the propodeum sculptured like the mesepisternum; dorsal 

 aspect of the propodeum rather coarsely punctato-rugose with the 

 rugosity more developed basally, with two low rounded carinae which 

 are subparaUel to near the base, when they diverge sharply; these 

 carinae become subobsolete apically ; first tergite one-fifth longer than 

 the second, the lateral margins slightly sinuate at the spiracles, the 

 dorsal aspect with two subcarinate, elevated portions which extend 

 almost to the apical margin at the apex of these raised areas is a 

 shallow fovea; first tergite coarsely coriarious with the strength of 

 the sculpture diminished apically; disco-cubital vein with a well- 

 defined stump; nervulus slightly postf ureal. Black; scape beneath, 

 anterior lateral margins of the scutum, the posterior angles of the pro- 

 notum, tegulae, a spot below on the mesepisternum, and four anterior 

 legs, yellowish or reddish yellow; posterior legs, except the tibiae 

 above and the entire posterior tarsi which are black, rufous; wings 

 yellowish hyahnc, vitreous, venation dark brown. 



Male. — Length 18 mm.; length of the antennae 15 mm. Except 

 for the sexual characters this agrees with the above description of 

 the female, but it has the following additional yellow markings: 

 Clypeus, mandibles, four longitudinal spots on the face and the 

 anterior margin of the pronotum and a spot in front of the interme- 

 diate coxae. 



Cocoon. — Elongate, cyhndrical, rounded at each end. Dark brown ; 

 composed of an opaque papery substance, in which is interwoven 

 irregular strands of silk. 



