2 PROCEEDINGS OF THE NATIONAL MUSEUM vol.81 



fore, that in this case these terms for fishes have been interpreted to 

 mean a dolphin and that these fish parasites have been erroneously 

 listed as parasites of cetaceans. 



In the compiled descriptions all measurements when less than 1 mm 

 have been given in microns, when more than 0.5/x the fraction has 

 been counted as 1^, and if less the fraction has been discarded. 



The trematodes of marine mammals which may be considered valid 

 or recognizable forms comprise 30 species belonging to nine families : 

 Fasciolidae Railliet, Echinostomatidae Looss, Troglotrematidae 

 Odhner, Opisthorchiidae Braun, Heteroplwidae Odhner, Paramphis- 

 tomatidae Fischoeder, Notocotylidae Liilie, Opisthotrematidae Poche, 

 and Rhabdiopoeidae Poche. These families may be differentiated 

 by the following key : 



KEY TO FAMILIES OF TEEMATODE PARASITES OF MABINE MAMMALS 



1. Body provided with two suckers; eggs without polar filaments 2. 



Body provided with only one sucker ; eggs with polar filaments 7. 



2. Acetabulum or ventral sucker situated at posterior end of body. 



Paraniphistomatidae (p. 41). 

 Acetabulum situated in anterior half of body 3. 



3. Anterior end of body provided with a kidney-shaped collar armed 



with one to two rows of large spines Echinostomatidae (p. 21). 



Anterior end of body without collar as above 4. 



4. Usually large flukes, either flat and leaflike, slightly flattened, 



or cylindrical ; cirrus pouch and cirrus present ; seminal re- 

 ceptacle very small or absent Fasciolidae (p. 3). 



Medium-sized to very small flukes, usually oval and flattened ; 

 cirrus pouch and cirrus absent; seminal receptacle large and 

 conspicuous 5. 



5. Body spindle shaped ; occurring in cysts, usually in pairs. 



Troglotrematidae (p. 23). 

 Body flat, not occurring in cysts 6. 



6. Body covered with small, scalelike spines ; acetabulum inclosed 



in the genital sinus ; parasites of the intestinal tract. 



Heterophyidae (p. 33). 

 Body usually without spines ; acetabulum not inclosed in the 

 genital sinus; parasites of the gall bladder or bile ducts. 



Opisthorchiidae (p. 25). 



7. Genital pore situated at extreme posterior end of body. 



Opisthotrematidae (p. 48). 



Genital pore near anterior end of body 8. 



S. "Ventral surface of body usually provided with longitudinal rows 

 of glands, or rugae ; vitellaria pretesticular ; without probo- 



scid complex in posterior part of body Notocotylidae (p. 44). 



Ventral surface of body without rows of glands, or rugae ; 

 vitellaria posttesticular ; proboscid complex in posterior part 

 of body Rhabdiopoeidae (p. 47). 



