NO. 6 gilbert: three new trematodes 99 



berance at the extreme posterior end. In extended compressed speci- 

 mens the collar is not visible. In contracted specimens there is a 

 weak muscular collar which projects slightly laterally and dorsally, 

 but is interrupted ventrally by a depression. The oral sucker is mus- 

 cular, subterminal, and measures 0.22 to 0.4 mm. long and 0.30 to 

 0.42 mm. wide. 



The mouth is located in the posterior portion of the oral sucker. 

 The esophagus is short, slightly less than the length of the oral 

 sucker. The ceca are simple, narrow, and unbranched, extending to 

 the posterior fourth of the body. Near their posterior ends the ceca 

 seem to twist considerably, resembling a corkscrew. The ceca do 

 not unite posteriorly, nor bow in at the testes. 



The common genital pore is located on the median line, one 

 fourth the body length from the anterior end. The testes are located 

 in the posterior half of the body, somewhat anterior to the termina- 

 tions of the ceca. They are round or oval, unlobed, Intercecal, tan- 

 dem, separated by about half their length. The cirrus sac is spherical 

 and surrounded by a layer of circular muscles. The seminal vesicle 

 opens into the posterior end of the cirrus sac, and a long ejacula- 

 tory duct passes through it. The cirrus is in the form of a stout 

 papilla projecting into a large chamber which surrounds all but its 

 basal portion. Longitudinal muscles line the cirrus chamber and also 

 cover the outer surface of the papilla (cirrus). The chamber of the 

 cirrus sac opens on the ventral surface of the body through the geni- 

 tal pore. The seminal vesicle is a voluminous, highly coiled tube to 

 the right of and posterior to the cirrus sac. It extends posteriorly 

 about one and one-half times the length of the cirrus sac. The more 

 anterior, prostatic portion of the vesicle is enlarged and coiled. This 

 part of the vesicle possesses an outer layer of longitudinal muscle, 

 and numerous prostatic cells which fill its greater portion (fig. 10). 

 The posterior portion of the vesicle is without the heavy muscle 

 layer or prostatic cells, and is the true seminal vesicle. 



The ovary is located on the mid-line just anterior to the anterior 

 testis. It is rounded, unlobed, and slightly smaller than the testes. 

 The shell gland is large, lying posterior to, and in most specimens, 

 a little to the right of the ovary. The gland is made up of many large 

 cells radiating about the oviduct which is coiled in the anterior por- 

 tion of the gland. A definite sheath surrounds the gland. Laurer's 

 canal is long, and opens dorsally anterior to the ovary. The vitelline 



