90 NEW GTRODACTYLOID TREMATODES PROM AUSTR.1LIAN FISHES, 



The mouth opens ventrally, some distance behind the anterior end. The 

 long buccal cavity communicates with a pharynx which passes almost vertically 

 upwards so that, in dorsal view, the latter appears spherical instead of ovoid. 

 The pharynx opens postero-dorsally into the intestine which is practically a 

 ring-shaped sinus with a large lumen, lined by a single layer of flattened 

 epithelial cells. At "either side of the pharynx is a mass of digestive glands 

 connected with the intestine. 



The cephalic glands have undergone a curious change in position owing to 

 the head being flattened transvei-sely and the glands coming to occupy a position 

 at the angles of the head. Their ducts consequently pass, not forward, but 

 inward. Three pairs of head-organs are present. There are two pairs of eyes, 

 situated well within the body-parenchyma, the anterior pair being very small 

 and the posterior more than, usually large. The brain could not be distinguished. 

 No trace of excretory system was recognisable. The ovoid testis lies practically 

 in the centre of the animal, and antero-laterally gives off a large uncoiled vas 

 deferens which passes forwards into a transversely-dilated vesicula seminalis. 

 The cirnis closely resembles that of Protogyroclactylue, as does also the curious 

 cirrus-sac. 



The female genitalia are more difficult to obseiwe. The ovary, which lies 

 below and somewhat in front of the testis, is strongly elongated transversely. 

 The uterus appears to be a short duct with a wide lumen. The nature of the 

 shell-gland could not be definitely made out, but it appears to be merely a 

 glandular thickening of the ootype. The comparatively large spherical egg 

 measures about .05 mm. in diameter and possesses a backwardly directed spine. 



The vitellaria are of the Protogyrodactylns type, i.e. there are long "yolk- 

 tubes," converging to form transverse ducts. Of these there are three, not two 

 as in that genus, one being situated in front of the ovary and the other two 

 posterior to it. The anterior transverse vitelline duct is formed by the con- 

 vergence of a very large number of elongated yolk-tubes, occupying the anterior 

 half of the body. Of thei posterior yolk-ducts, one is situated ventrally, the 

 other more dorsally. The dorsal posterior transverse duct lies immediately be- 

 hind the ovai-y and receives the secretion from two systems of yolk-tubes, a 

 posterior and an anterior, on either side. This transvei-se duct has a com- 

 munication with the intestine, similai- to that of Protogyrodactylus. The ventral 

 posterior transverse duct, which possesses no communication with the intestine, 

 is rather narrower and lies a little behind the dorsal duct. The three transverse 

 yolk-duets are joined by a common median duct, running below the ovary and 

 apparently opening into the ootype. 



Found on the gills of Therapon fuliginosus Maeleay, from the Thomson 

 Elver, at Longreach, Central Queensland. 



Family II. GYRODACTYLIDAE Van Beneden and Hesse, 1863.— emend. J. & T. 



(Syn. Amphibdellidae Carus, 1885.) 



These are elongated Gyrodactyloidea with well developed clas.piiig disc 

 which may or may not be distinctly marked off from the remainder of the body, 

 and may, in the highest members of the group, bear suckers. The disc bears 

 large and small hooks, sometimes forming a ehitinous armature of great com- 

 plexity. 



Cephalic glands are preseoit and always open to the exterior by means of 

 well defined head-organs. 



The pharynx may be large or small; the intestine single or with two limbs, 



