80 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



the enclosed plates, is visible occupies more than one-third the width 

 of the ventral aspect of abdomen. 



The plates, both ventral and dorsal, are at once distinguished 

 throughout their extent from the membrane by being clothed with 

 bristly hairs. 



The above description was drawn from a specimen collected by 

 F. C. Pratt, at Poolesville, Maryland, July 9. The abdomen was 

 detached and put under the microscope. 



CEDEMASOMA, gen. nov. 



This form (male) agrees with the description of Wahlbergia 

 brevipennis H. Loew, except that the fourth vein is bent at a 

 rounded angle, and hind crossvein is not strongly oblique. The 

 hind crossvein is straight, almost at right angles to the fourth vein, 

 hardly nearer to bend of latter than to small crossvein, and at right 

 angles to fifth vein. The petiole of apical cell is slightly longer than 

 small crossvein, but not twice as long — about one and one-fourth 

 times as long. The abdomen is swollen and strongly convex above, 

 wider than the thorax, exactly oval in outline from above, the wider 

 end forward, absolutely without macrochaetae. Palpi are extremely 

 small, almost atrophied, very slender and quite short. Antennae 

 as long as face, second joint almost as long as third. No orbital 

 bristles. Wings very short and narrow. The claws are about as 

 long as last tarsal joint. Type, the following species : 



CEdemasoma nuda, sp. nov. 



One male, Ormsby County, Nevada, July 6, C. F. Baker, Coll. 



Length, 6 mm. ; of wing, 4 mm. Face, parafacials and para- 

 frontals from above silvery white pruinose, blackish from in front, 

 the silvery extending on cheeks. Frontalia silvery white pruinose, 

 with a faint brassy tinge or a golden reflection. Abdomen densely 

 covered with moderately short and fine brown or black hairs, and 

 entirely without bristles, wholly yellowish red or brownish red. The 

 mesoscutum is silvery pollinose in front of suture, but it does not 

 show well in some lights. Tegulae white. Palpi pale reddish 

 brownish in color. All the rest of insect is black, except the clear 

 wings, which are yellowish at base. Otherwise agrees with Loew's 

 description of Wahlbergia "brevipennis. 



This form apparently belongs in the neighborhood of Gymnosoma, 

 indicated by the absence of macrochaetae and the possession of a 

 swollen abdomen. JVahlb. brevipennis H. Loew is this genus, but 

 a different species. Loew's specimen is a female from Nebraska, 



