420 PROCEEDINGS OF THE NATIONAL MUSEUM vol.86 



Description. — External appearance typical of the genus ; type speci- 

 men (fig. 47, a) 5 mm long, 1.8 mm wide, contracted, hence longer and 

 slenderer in life. Head bluntly triangular with blunt auricles and 

 usual two eyes. Pharynx behind the middle. 



Color. — Black above, evenly granular, auricles lighter, dark brown 

 below. 



Histology. — Dorsal epi^ielium very thickly beset with rhabdites 

 (fig. 47, h) \ beneath the dorsal epithelium a very wide pigmented 

 region in the parenchyma; just inside this pigmented zone occur the 

 numerous rhabdite-forming gland cells (fig. 47, &). Rhabdites, pig- 

 ment, and rhabdite-forming cells much fewer ventrally than dorsally. 

 Adhesive zone (fig. 47, h) very conspicuous at the posterior end, less 

 so at the anterior end ; otherwise this species is rather devoid of gland 

 cells. Longitudinal fibers of the subepithelial muscle layer well 

 developed. 



Reproductive system. — Typical of the genus. Testes numerous, 

 ventral, of moderate size, extending from just behind the ovaries to 

 the posterior end. Vasa deferentia forming tlie usual expanded "false" 

 seminal vesicles packed with sperm alongside the pharynx to near 

 their entrance into the penis bulb. Penis typical of the genus, with 

 evident bulb and papilla (fig. 47, c). Penis bulb of rounded form con- 

 taining many muscle fibers coursing parallel to its external contour. 

 The slender terminations of the two vasa deferentia pass separately 

 and without enlargement through the penis bulb and open into the 

 sides of a rounded cavity, the true seminal vesicle, in the penis bulb. 

 This cavity is lined by a tall glandular epithelium, which receives the 

 gi'anular outlets of gland cells situated in the parenchyma of the penis 

 bulb. Penis papilla short, truncate, with a central depression con- 

 taining a papilla on which the ejaculatory duct opens. The ejaculatorv 

 duct is directly continuous with the seminal vesicle in the penis bulb 

 and is lined by a cuboidal epithelium. Penis papilla clothed with a 

 thin epithelium l)eneath which is a thick layer of circular musclas. 

 Its interior consists of parenchyma with loose longitudinal muscle 

 fibers continuous with those encircling the penis bulb. Ovaries typical, 

 somewhat more posterior to the ej-es than the latter are to the anterior 

 tip. The oviducts proceed posteriorly and enter separately the bursa 

 stalk some distance above the entrance of the latter into the genital 

 atrium. Copulatory bursa of moderate size in usual position between 

 the penis bulb and the end of the pharyngeal chamber, saclike, lined by 

 a tall epithelium, and with a thin layer of muscle fibers on its external 

 surface. Bursa stalk fairly large, lined by a tall ciliated epithelium, 

 clothed externally with a well -developed muscle layer of intermingled 

 circular and longitudinal fibers. Genital atrium divided by a descend- 



