32 



" TERRA NOVA" EXPEDITION. 



Parasite. — Male 9 mm. long. Female 10 mm. Both are flattened forms, but 

 whether this is due to treatment after death or not cannot he stated. The greatest 

 breadth of both male and female is 2 "5 mm. The worms are almond-shaped, the male 

 tapering more rapidly towards the posterior end than the female. The proboscis 

 (PI. II, fig. 13, a) measures 2 mm., the hook-bearing portion being 0*5 mm. long. The 

 hooks on the rostellum are arranged in fourteen linear series, 

 each having eight hooks. There are no cuticular swellings around 

 the hooks. In these features of the proboscis these forms differ 

 from the succeeding species, to which they show considerable 

 i resemblance. The lemnisci (L V) are stout and club-shaped, 



] laving a length double that of the internal part of the pro- 

 boscis. The testes ('/, d') are oval, 0"2 mm. by 0'25 mm., are 

 diagonally situated, and occupy the third fifth of the body. 

 The prostatic glands are aggregated into two large masses. 



11. Echinorhynchus rennicki, Leip. and Atk. (PI. II, fig. 15. 

 Text-fig. 3.) 



Echinorhynchus rennicki, Leiper and Atkinson, Proc. Zool. Soc, 1914, p. 223. 



Male 3 • 7 mm. long. Female 4 mm. Proboscis 1 mm. Hook-bearing 

 rostellum 0*3 mm. Hooks in 12 linear series of 6 each. Those of alternate 

 rows are in line transversely. Each hook protrudes from a transparent 

 / cuticular lapel. Lemnisci long and slender. 



Host. — These medium sized thorn-headed worms were 

 obtained from Trematomus bernacchii at Cape Evans, Lat. 77° 38' 

 S. (Stat. 326). 



Parasite. — The male and female of this species are similar 

 in shape, and can only be differentiated by their internal structure 

 save where, in the male, the bursa is extruded posteriorly. 

 The greatest breadth is quickly attained in the anterior half of the 

 body. The posterior half tapers gradually and uniformly to the 

 tail. The male measures 3 ■ 7 mm. iu leno th and 0 ' 8 mm. in 



Fig. 3. — Echinorhynchus 

 rennicki : Female, 



tilled with eggs, breadth. The female averages 4 mm. by 1 mm. The' proboscis 



The cuticular lapels (pp jj fig _ 15> ^ iu t } ie male j g x mm ; [ n t ] ie f ema l e i. 2 mm. 

 covering the hooks i-iii- • i ■ ^ r. i ^ 



on the proboscis are lon S > the hook-bearing portion being 0*3 mm. by 0'12 mm. 



shown. There are twelve longitudinal rows of hooks with six hooks in 



each row. The hooks of every second row are in line trans- 

 versely. A striking feature of the proboscis is the presence of a transparent cuticular 

 swelling from which each hook protrudes. By this character alone the species 

 can be distinguished readily from the other forms found in the same host. The 

 lemnisci (Fig. 15, I, I') are long slender bodies, from the posterior end of which a 

 bundle of muscle-fibres passes backwards and becomes attached to the body-wall half 



