ART. 13 TREMATODE PARASITES OF MARINE MAMMALS PRICE 49 



cirrus; testes intercecal or extracecal, situated in the same transverse 

 plane in the posterior part of body. Ovary either dextral or sinistral 

 in position, pretesticular ; Mehlis's gland postovarial ; seminal recep- 

 tacle present; Laurer's canal present or absent; vitellaria weakly 

 developed, intercecal, pretesticular; uterus long and slender, occupy- 

 ing the greater portion of the central part of body, usually confined 

 to the intercecal field. Eggs with long polar filaments. Parasites 

 of respiratory passages of Sirenia. 



Type genus. — O-pisthotrema Fischer, 1883. 



KEY TO THE GENERA OF OPISTHOTREMATIDAE 



1. Testes extracecal Opisthotrema (p. 49). 



Testes intercecal Pulmonicola (p. 55). 



Genus OPISTHOTREMA Fischer, 1883 



Synonym. — Cochleotrema Travassos and Vogelsang, 1931. 



Generic diagnosis. — Opisthotrematidae : Body oval to piriform in 

 shape, flattened dorsoventrally, dorsum strongly arched and venter 

 strongly concave ; margin of body may or may not be provided with 

 a muscular rim. Cuticle of ventral surface spiny. Oral sucker ven- 

 tral, situated a short distance from the anterior margin of body; 

 pharynx absent; esophagus slender and of medium length; intes- 

 tinal ceca more or less sinuous and extending into the posterior fourth 

 of body. Excretory pore dorsal and somewhat removed from the 

 posterior margin; excretory vesicle tubular and provided with lat- 

 eral branches. Genital pores at posterior end of body ; cirrus pouch 

 long and slender, containing a slender, convoluted seminal vesicle 

 and a long, slender, protrusible cirrus; testes lobed, situated extra- 

 cecally in the same transverse plane in the posterior part of body. 

 Ovary lobed, to the right or left of the median line anterior to and 

 separated from the testis on the corresponding side by the intestinal 

 cecum, which passes between them; Mehlis's gland well developed; 

 seminal receptacle present; Laurer's canal present or absent; vitel- 

 laria intercecal and consist of a grapelike mass of follicles on each 

 side of median line, or of a mass of irregular follicles in the median 

 field. Uterus long, slender, and convoluted, occupying the greater 

 part of the central portion of the body ; vagina long, slender, slightly 

 sinuous, and provided with relatively strong muscular walls. Eggs 

 oval and provided with a slender filament at each pole. Parasites 

 of the respiratory tract and eustachian tubes of Sirenia. 



Type species. — Opisthotrema cochleare Fischer, 1883 {=Mono- 

 stomum datjonis Leuckart, 1874) . 



Remarks. — The foregoing diagnosis is based on the characters 

 common for the two species which are described later. The writer 

 118893—32 4 



