34 



" TERRA NOVA" EXPEDITION. 



TREMATODA. 



DISTOMOIDEA. 

 Fam. HEMIUKIDAE. 

 Rem/' was, Kud. 1809. 



13. Thmiurus oatesi, Leip. and Atk. (PI. Ill, fig. 17.) 



Hemiurus oatesi, Leiper and Atkinson, Proc. Zool. Soc, 1914, p. 224. 



Length 2 mm. Abdomen present but retracted wholly. Skin sharply striated. Ventral sucker 

 0 • 34 mm. in diameter, twice that of the oral sucker. Enormous muscular seminal vesicle. Yolk-masses 

 compact, lobulated. Eggs exceedingly numerous and small. 



Host. — Six specimens of this species were collected from the fish Trematomus 

 bernacchii. 



Parasite. — An average example is 2 mm. long, bluntly rounded at both ends, but 

 tapering more at the anterior than at the posterior extremity. The greatest breadth, 

 0'68mm., occurs just behind the middle of the body, at the level of the yolk-glands. 

 There is a well-defined " abdomen " (PI. Ill, fig. 17, c/), which is wholly retracted in the 

 preserved state. The skin is sharply striated transversely, and these striae, although 

 best seen on the ventral aspect, extend to the dorsum. The ventral sucker (b) is near 

 the oral sucker (a), and is about twice its size, measuring 0 " 34 mm. in external and 

 0 " 18 mm. iu internal diameter. Owing to contraction the mouth and the oral sucker 

 are somewhat bent ventrally. The pharynx is globular, measuring 0 " 1 2 mm. longi- 

 tudinally and 0 • 1 mm. transversely. The two main gut-branches ((/, </) terminate 

 blindly some way in front of the base of the abdomen, whereas in other species they 

 usually extend for a varying distance into this structure. The genital pore (gp) opens 

 immediately behind the lip of the oral sucker. A very noticeable feature is the enormous 

 seminal vesicle (sv), which has a thick muscular coat. The yolk-glands (//, '/') are 

 compact and lobulated, and lie in the middle region of the body between the " abdomen" 

 and the ventral sucker. Immediately in front of these is a large ovary (ov) 0 ■ 34 mm. 

 transversely and 0'16mm. longitudinally, and anterior to this two testes (t, t'), 

 0*2 mm. x Oimm., situated slightly diagonally to one another. The uterus (at) is 

 filled with eggs, 0'05imn. x 0*03 mm., and occupies most of the interstices between 

 the posterior lobule of the yolk-glands and the ventral sucker. The eggs are very small 

 as compared with those in the succeeding Hemiuridae. 



Aponurus, Looss. 



14. Aponurus bowersi, Leip. and Atk. (PI. Ill, fig. 18.) 



Aponurus bowersi, Leiper and Atkinson, Proc. Zool. Soc, 1914, p. 224. 



Length 1 mm. The oral sucker has a characteristic fleshy lip along its dorsal rim only. Gut-branches 

 greatly dilated, and extending to the posterior end of the body. The yolk-glands are peculiar : two 

 half-moon shaped solid masses lying in apposition, immediately in front of the ovary. 



.Host. — Trematomus bernacch it. 



