84 bulletin: museum of comparative zoology. 



2. Large species, length 8.5 mm., last section of the radius recurved. 



M. lapideus, sp. now 

 Smaller, less than 6 mm., last section of the radius straight. 



M. carceratus, sp. now 



3. Petiole of areolet long, nearly as long as the inner side of the 



areolet, stigma narrow M. abolitus, sp. nov. 



Petiole shorter or obsolete 4. 



4. Stigma slender, lanceolate 5. 



Stigma ovate or broadly ovate 6. 



5. Areolet distinctly petiolate, the petiole distinct. 



M. revocatus, sp. nov. 

 Petiole obsolete 7. 



6. First section of the radius much longer than the thickness of the 



stigma M . terrosus, sp. nov. 



First section of the radius not or scarcely longer than the thickness 

 of the stigma M. cataclysmi, sp. nov. 



7. Areolet regularly rhombic .... M. aboriginalis, sp. nov. 

 Areolet rhomboidal, distinctly oblique. M . dormitorius, sp. nov. 



Mesochorus lapideus, sp. nov. (Fig. 64.) 



Female. Length about 8.5 mm. Brown, varied with darker; wings hya- 

 line. Head probably black; antennae fuscous, about 32-jointed, rather 

 stout, the basal flagellar joints about three times as long as thick ; those toward 

 the apex quadrate. Thorax brownish or blackish, varied on the pleurae with 

 lighter. Metanotum areolated, the basal and middle lateral areas separated, 



but indistinctly so. Ab- 

 domen brown or ferrugi- 

 nous, the petiole and spot 

 at base of second segment 

 black. Ovipositor short, 

 slightly curved downward 

 at the tip. Coxae and 

 Fig. 64.— Mesochorus lapideus, sp. nov. Typq, l egs black, tarsi light 



brown, with darker tips. 

 Marginal cell long and narrow, the last section of the radius curved inwardly 

 so that it bulges into the marginal cell ; fully three times as long as the first 

 section. Stigma lanceolate, but moderately broad. Areolet large, obliquely 

 rhomboidal, quite broadly sessile above; submedian cell longer than the 

 median. 



Type.— No. 2276, M. C. Z., Florissant, Col. (No. 11,421, S. H. 



Scudder Coll.). 



