26 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.81 



KEY TO GENERA OF OPISTHORCHnNAB OCCURRING IN MARINE MAMMALS 



1. Uterine coils extend laterally beyond limits of intestinal ceca. 



Cyclorchis (p. 28). 

 Uterine coils do not extend laterally beyond limits of intestinal 

 ceca 2. 



2. Vitellaria divided into two distinct regions by a break at the 



level of the ovary Amphimerus (p. 29). 



Vitellaria not divided into tvpo regions Opisthorcliis (p. 26). 



Genus OPISTHORCHIS R. Blanchard, 1895 



Generic diagnosis. — Opisthorchiinae : Body elongated, flattened, 

 anterior end attenuated, posterior end broader. Cuticle generally 

 smooth, without spines. Excretory vesicle Y shaped, with S-shaped 

 stem and short branches. Cirrus pouch absent; testes usually lobed, 

 situated in posterior part of body and placed obliquely to the long 

 axis of the body. Ovary simple or lobate, pretesticular ; seminal 

 receptacle prominent, postovarial; Laurer's canal present. Uterus 

 with numerous transverse loops confined to intercecal field, not ex- 

 tending anteriorly beyond acetabulum. Vitellaria moderately de- 

 veloped, extracecal, not extending anteriorly beyond level of aceta- 

 bulum or posteriorly beyond level of ovary. Parasites of bile ducts 

 of mammals, birds, and fishes. 



2'ype species. — Opisthorchis felineus (Rivolta, 1884) R. Blanchard, 

 1895=6*. tenuicollis (Rudolphi, 1819). 



OPISTHORCHIS TENUICOLLIS (Rndolphi, 1819) Stiles and Hassall, 1896 



Plate 7, Figures 27, 28 



Synonyms. — Distoma tenuicollis Rudolphi, 1819, p. 93; D. conus 

 Gurlt, 1831, p. 193, not Creplin, 1870; D. lanceolatmn von Siebold, 

 1836, p. 113, not Rudolphi, 1803 ; D. felineum Rivolta, 1884, pp. 20- 

 28; D. viverrini Poirier, 1886, pp. 116-130; Opisthorchis felineus 

 (Rivolta, 1884) R. Blanchard, 1895, p. 217; 0. viverrini (Poirier, 

 1886) Stiles and Hassall, 1896, p. 155; O. tenuicollis- felineus Looss, 

 1899, p. 678. 



Description.— Opisthorchis: Body flat, 6.5 mm to 8.5 mm long by 

 2.1 mm to 2.2 mm wide, anterior end somewhat more attenuated 

 than posterior end. Cuticle smooth and without spines. Oral sucker 

 subterminal, 320/* to 340/x. in diameter; acetabulum 260;a to 320/1, long 

 by 300/A to 360/A wide, situated 1.4 mm to 1.6 mm from the anterior 

 end of body. Pharynx ovoid to piriform in shape, 200/x long by 

 140/A to 160/z, wide; esophagus 80/a to 140/x, long; intestinal ceca 

 slender and extending to near posterior end of body, the left cecum 

 being slightly shorter than the right. Excretory vesicle Y shaped, 

 with a long sigmoid stem and short branches. Genital aperture im- 

 mediately cephalad of acetabulum. Seminal vesicle more or less 



