110 AUSTRALIAN ENTOZOA, III., 



species approaches the characters of that ^enus. Instead of being 

 the simple, almost solid plug characteristic of Hemistomum, the 

 clinging plug in this species consists of two parallel plates folded 

 in a scroll-like manner towards one another (PI. v., iSg. 7). 



The oral sucker is of moderate size (0-17 mm.) and the pharynx 

 smaller; the ventral sucker (0-25 mm.) is very large and stalked, 

 being raised up from the body-surface on a thick projection or 

 stalk, about equal in length to the diameter of the sucker. On 

 €ach side of the oral sucker is a group of very large unicellular 

 glands, which open into a crescentic depression from the ventral 

 body-surface. 



The bursa copulatrix, which, together with the genital papilla, 

 is fairly well developed, is turned to open dorsally. The ovary 

 is situated far forwards in the cylindrical body-region, near its 

 junction with the anterior body-region. Behind it are placed, 

 one behind the other, two large testes. The uterus in its hinder 

 part has its walls raised up into a number of transverse folds or 

 rido;es. 



The vitelline glands, which are very numerous, occur along the 

 whole length of the ventral aspect of the posterior body-part. 



Found in the duodenum of the Black Swan, Cygnus ati^atus, 

 Lath. Collected at Duckmaloi River, N.S.W. 



HoLOSTOMUM HiLLii, sp.n. 

 (Plate vi., figs. 1-8.) 



Length 6 "9-8 -2 mm. Anterior body-region well marked off 

 from the posterior region, one-seventh of the entire length. 



The clinging apparatus or plug, which lies in the cavity of the 

 cup-like anterior body-part, consists of two parts: a cushion-like 

 mass, with a long base of attachment to the ventral body-wall, 

 situated on the dorsal side of the cup and forming the dorsal mass 

 of plug, and a ventral part consisting of a lamellous sheet, which 

 may be described as H -shaped. It arises posteriorly from the 

 ventral wall of the cup as two lateral flaps which, at about the 

 middle of their length, become fused together for a short space 



