ART. 13 TREMATODE PARASITES OF MARINE MAMMALS — PRICE 43 



intestinal ceca and two longitudinal vessels which lie ventrally of 

 the ceca. The dorsal vessels extend the full length of the body and 

 terminate in a number of short, dilated branches. Each vessel gives 

 off about 15 primary branches, which extend lateroventrally and 

 bifurcate to form secondary branches. The secondary branches usu- 

 ally bifurcate to form tertiary branches, each of which terminates 

 in a bulbous swelling near the ventral surface of the body. A num- 

 ber of ventral branches are also given off from the main dorsal 

 canals, but their number and course can not be determined with cer- 

 tainty. The ventral longitudinal canals extend the full length of 

 the intestinal ceca and give off a number of branches, both medially 

 and laterally, which branch again and again and finally terminate 

 in large bulbous swellings; these branches and swellings cover the 

 entire ventral surface of the body beneath the dermomuscular layer. 

 The genital pore is situated immediately caudad of the intestinal 

 bifurcation and is surrounded by a weakly muscular genital sucker. 

 In immature specimens the suckerlike arrangement of the muscular 

 fibers is not so distinct as in more mature specimens. The genital 

 opening communicates with a genital sinus into which projects the 

 prominent genital papilla. The greatly convoluted seminal vesicle 

 lies free in the parenchyma dorsad of the genital pore. The proxi- 

 mal portion of the ejaculatory duct is inclosed in a muscular saclike 

 structure, but distally this sac is very feebly developed or absent. 

 The ejaculatory duct unites with the vagina or metraterm to form 

 a hermaphroditic canal, which opens into the genital sinus at the 

 summit of the genital papilla. The testes are X shaped in mature 

 specimens and almost spherical in immature specimens; they are 

 situated in the median field and are tandem in position. The ovary 

 is almost spherical, about 30/^, in diameter, median in position, and 

 situated about midway between the posterior testis and acetabulum. 

 Mehlis's gland well developed, dorsad of ovary. Laurer's canal is 

 very slender and opens in the mid-dorsal line a short distance 

 cephalad of the excretory j^ore. The vitellaria are extracecal, except 

 for a few follicles, whicli are distributed intercecally immediately 

 in front of the acetabulum, and extend anteriorly beyond the intes- 

 tinal bifurcation. The uterus extends anteriorly in the median line, 

 dorsal to testes, to the level of the cephalic margin of the anterior 

 testis, and then turns ventrally and terminates in a weakly muscular 

 vagina or metraterm. The proximal portion of the uterus may be 

 filled with spermatozoa, and constitutes a receptaculum seminis 

 uterinum. The eggs are oval, about 150;a long by 90/x wide, and thin 

 shelled. 



Hosts. — Manatus exunguis Natterer ( = ? Trlchechus inunguis 

 Pelzeln), Trlchechus latirostrls (syn. Manatus latirostris) , and T, 

 senegalensis. 



