114 AUSTRALIAN ENTOZOA, III., 



The oral sucker is of medium size (0*2 mm. diara.); the pharynx 

 is about the same size: both are spherical in shape : the cesophagus 

 is of some length (0-35 mm.). The ventral sucker, though well 

 developed (0-2 mm. long, and 0*14 mm. broad), is completely- 

 covered over by the plug of the clinging apparatus, and lies 

 embedded in its tissues and those of the ventral part of the body, 

 communicating with the exterior only by means of a narrow thin- 

 walled canal which opens into the cavity of the hollow plug. 



A number of very strong bands of longitudinal muscle occur in 

 the posterior body-region : near its junction with the anterior 

 body-region they are gathered into several well marked bundles 

 (PL vii., fig. 8), but towards the posterior end they have spread 

 out and tend to become a complete circular layer of longitudinal 

 fibres. The excretory system is very well developed, and in the 

 front part of the posterior body-region consists of a number of 

 well marked cavities. The vitelline glands do not occur in the 

 anterior body-region nor in the walls of the bursa copulatrix, but 

 in the intervening portion they are numerous and well developed. 

 The testes are large and divided up into a number of lobes 

 (PI. vii., fig. 6). The genital papilla opens on the exterior by a 

 cleft-like aperture which divides it into two parts (fig. 7). 



Found in the duodenum of the Crested Tern, Sterna bergii, 

 Licht., at Broken Bay. 



Many of the figures were drawn by my wife. 



Reference letters. 



b.c, bursa copulatrix. — c.c, cavity of cup. — cav.p., cavity of plug. — c.p., 

 clinging plug. — dAv., dorsal wall of plug. — eg., eggs. — ex., excretory vessel. 

 —f.d., female duct. — gl, glands. — g.p., genital papilla. — int., intestine. — 

 l.m., longitudinal muscle. — ^.^., lobes of testes. — m.d., mouths of ducts. — 

 <es., oesophagus. — o.s., oral sucker. — ov., ovary. — ovid., oviduct. — ph., 

 pharynx; pr^^. and pr^., processes arising from the ventral wall of the cup. — 

 rf.p., reflexed process of plug. — s.ni., sphincter muscle. — t^. and<2-> ^^stes. — 

 ?(./., united posterior parts of the lateral folds. — ut., uterus. — v.d., vas 

 deferens. — y.^., vitelline glands. — vit.d., vitelline duct. — r.s., ventral sucker. 

 — v.sem., vesicula seminalis. — v.io., ventral wall of plug. 



