174 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



anterior genital pore, shorter ceca, its more posteriorly located seminal 

 receptacle, its fused vitellaria, and its completely separated testicular 

 zones. 



BRACHYLECITHUM DELICATUM, new species 



Figure 37, g-l 



Diagnosis. — Body thin, semitransparent, elongated, with almost 

 parallel sides and rounded interior and tapering posterior ends; it 

 measures 1.43 to 2.18 mm. long by O.IT to 0.20 mm. wide in region 

 between posterior testis and vitellaria. Cuticle thin, aspinose, with 

 fine transverse ridges, and with small sensory papillae on margins of 

 body in some specimens. Oral sucker subterminal to small liplike 

 anterior end of body, weakly muscular, elongated oval, 0.10 to 0.13 mm. 

 long by 0.08 to 0.10 mm. wide. Acetabulum weakly muscular, pro- 

 trusible, 0.10 to 0.14 mm. in diameter, with center protruded (fig. 37, 

 h), in anterior fourth of body. Ratio of width of oral sucker to 

 acetabulum 1 : 1.07 to 1.41. Prepharynx absent. Pharynx muscular, 

 globular, 0.03 to 0.04 mm. long by 0.03 mm. wide. Esophagus very 

 thin walled, slender, slightly wavy, bifurcating from one-half to three- 

 fifths of distance from oral sucker to acetabulum. Ceca thin walled, 

 of medium width, slightly wavy, with extreme terminal portions 

 slightly dilated, terminating unevenly in zone of vitellaria or just 

 posterior to that zone. Excretory pore terminal. Excretory vesicle 

 thin-walled, tubular, narrow, extending anteriad to about middle of 

 vitellaria. Genital pore median, ventral to intestinal bifurcation or 

 slightly anterior to it. Testes round to oval, approximately equal in 

 size, 0.08 to 0.17 mm. long by 0.07 to 0.14 mm. wide, with smooth to 

 slightly lobed margins (fig. 37, i) in oldest specimen, slightly oblique 

 in position. Anterior testis located immediately posterior to acetabu- 

 lum or separated from it by a single uterine loop; posterior testis 

 entirely behind anterior one. Vasa efferentia uniting just in front of 

 anterior testis to form a short vas deferens. Cirrus sac elongated- 

 pyriform, 0.09 to 0.12 mm. long by 0.03 to 0.05 mm. wide, containing 

 convoluted seminal vesicle, ejaculatory duct and eversible cirrus, with 

 its posterior end at or slightly below cephalic margin of acetabuhmi. 

 Ovary round to oval in shape, 0.05 to 0.12 mm. in diameter, with 

 smooth to slightly irregular margins, on midline or slightly to one or 

 other side of body, separated from posterior testis by one loop of 

 ascending uterus. Seminal receptacle globular, posterior to ovary, 

 midway between ovary and vitellaria. Mehlis' gland and yolk reser- 

 voir posteromedial to seminal receptacle. Laurer's canal not ob- 

 served. Vitellaria (fig. 37, g, j-l) consisting of 7 to 10 medium-sized 

 irregular or transversely elongated follicles on each side of body. 

 Vitelline ducts arise from anterior follicles on each side and pass 



