152 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



joints is also characteristic. It belongs to the typical Xenidae, in 

 that it has four-jointed antennae, four-jointed tarsi, and two-jointed 

 palpi. 



i. APRACTELYTRA SCHWARZI Pierce (1908). 



Xenos schwarzi Pierce in determinations. 



Host. — Unknown. 



Locality. — Washington, D. C. (pi. 10, figs. 3, 4, 5, 6). 



Male. — Length' 1.66 mm. Wing expanse 4 mm. Black, with 

 whitish pubescence. Wings milky, very pubescent. Last ventral 

 segment brownish; cedeagus yellow. Under parts lighter. Head 

 transverse, eyes stalked, but not prominently, vertex roundingly 

 produced above each antenna. Antennae compact, with branches 

 closely flattened, equaling the distance from the inside of one eye to 

 the outside of the other, or subequaling the length of the elytra. 

 Maxilla? and palpi subequal; the maxilla from a side view, obliquely 

 truncate beneath, and thicker than the palpus ; palpus slightly taper- 

 ing, rounded at apex. Mandibles short, acute, slightly curved, not 

 much longer than first joint of palpi. Pronotum narrow, bandlike; 

 mesonotum subequal and similar. Metanotum very long; prae- 

 scutum keystone shape; scuti elongate subtriangular with apices at 

 posterior angles of praescutum distant; scutellum subequal to prae- 

 scutum in size and shape but inverted, with broadest side apical; 

 postlumbium transverse semielliptical; femoralia short; postscu- 

 tellum linear elongate; over twice as long as broad, with apices squarely 

 rounded. Genitalia consisting of tenth segment overlapping the 

 troughlike cavity of the ninth segment, which is bounded by the flap- 

 like edges of the last ventral segment and apically terminated by a 

 short cedeagus. In the type specimen the cedeagus is not reflexed 

 and shielded by the tenth segment, but is directed backward. The 

 sinuation is slight until about the posterior one-fifth, where the tube 

 is abruptly turned downward. The apex is abruptly acute. 



Type.— Two males, Cat. No. 9827, U.S.N.M. 



Named in honor of Mr. E. A. Schwarz, from whose collection it is 

 described. 



4. Subfamily CRAWFOBDIN^ Pierce, 1908. 



Type genus. — Crawfordia Pierce (1908). 



Maxillae three-jointed, apparently; postlumbium as large as in 

 Stylops, Halictoxenos, and Apractelytra, thus linking the bee-parasite 

 genera; cedeagus very different from that of the three genera men- 

 tioned. 



The subfamily includes one genus: Crawfordia Pierce, parasitic on 

 Panurginus; America. 



