HELMINTH PARASITES OF BIRDS — DENTON AND BYRD 173 



licult to visualize in fixed specimens, of medium width, straight to 

 slightly wavy, terminating unevenly just in front of vitellaria or some- 

 where within vitelline zone. Excretory pore terminal. Genital pore 

 median, anterior to bifurcation of intestine, from one-half to three- 

 fourths the distance from oral sucker to acetabulum. Testes approxi- 

 mately equal in size, 0.06 to 0.18 mm. long by 0.07 to 0.15 mm. wide, 

 round to oval, with smooth to slightly lobed margins, slightly oblique 

 in position. Anterior testis immediately posterior to acetabulum or 

 depending on state of contraction of body, may be separated from that 

 organ by one to three uterine loops. Posterior testis entirely behind 

 zone of anterior testis. Cirrus sac elongated-pyriform, 0.13 to 0.15 

 mm. long by 0.04 to 0.05 mm. wide, containing convoluted seminal 

 vesicle, ejaculatory duct, and eversible cirrus, extending posteriorly 

 far enough for one-third to two-thirds of its length to lie dorsally to 

 acetabulum. Ovary entire, round to transversely oval, 0.04 to 0.08 

 mm. long by 0.08 to 0.11 mm. wide, on midline or slightly to one or 

 other side of that line, separated from posterior testis by one or two 

 loops of uterus. Seminal receptacle globular, entirely posterior to 

 ovary, against dorsal body wall. Mehlis' gland and yolk reservoir 

 median to seminal receptacle. Laurer's canal not observed. Vitel- 

 laria (fig. 37, c-f) consisting of 6 to 14 large irregular masses of yolk 

 cells, individual masses joined together by distinct ducts and glands 

 usually joined across body at their anterior limits to form a wide con- 

 necting bridge just beneath dorsal body wall. Uterus greatly convo- 

 luted, with rather indistinct loops, filling most of body posterior to 

 vitellaria, passing anteriorly between and ventrally to vitellaria, ven- 

 trally to middle or either margin of ovary, to dorsal side of body be- 

 tween posterior testis and ovary, either right or left side of posterior 

 testis between testes, dorsally to acetabulum where it forms several 

 loops before reaching genital pore. Mature ova few in number, dark 

 brown in color, 39/* to 4Afi long by 22)Lt to 28/x wide. 



Host. — Seiurus aurocapillus (Linnaeus). 



Habitat. — ^Liver. 



Locality. — Virginia : Mountain Lake. 



Type specimen.— U.^.l^.M. Helm. Coll. No. 37118. 



Remarks. — Brachylecithum seiuricwm, is described from 18 speci- 

 mens from the liver of one of 14 ovenbirds, Seiurus aurocapillus. In 

 its combination of characters of having a slender body with suckers 

 approximately equal in size, testes not exceeding acetabulum in size, 

 ovary slightly smaller than testes, ceca not extending posterior to 

 vitellaria, genital pore anterior to intestinal bifurcation and the fused 

 vitellaria, B. seiuricimi is unique among the already described species 

 of the genus. From B. americanumi and B. m,oorei, which it super- 

 ficially resembles, B. seiu/ricum is readily distinguished by its more 



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