BY T. HABVEY JOHN.STON AXD 0." W. TIEGS. 109 



but prostate glands were not seen. The large "cirrus-glands" are already well 

 developed, as is also the yolk system. The disc, though at fli'st sight quite 

 diffei-ent from' that of the adult, is built on the same plan (Pi. xx., fig. 72). It 

 is proportionally much larger than the adult disc, which evidently becomes 

 formed from that of the young woi-m by the addition of a quantity of "padding 

 tissue" which is plainly visible within it, giving it a more spherical appearance. 

 In slightly lai-ger worms this immature form of the disc is retained, but the 

 cephalic glands are already of the adult type. 



Found on the gills of the golden perch, PlectropUtes ambiguiis Richardson, 

 from the Thomson River at LongTeach, Central Queensland. 



18. Emplburodiscus, n.gen. 



Lepidotreminae. In this genus the scale-like papiUae cover practically the 

 whole of the body, being absent only in the head region. The scales of the 

 squamodisc are arranged generally in from se\-en to nine rows. A large number 

 (25 to 30) of sharp accessoi-y hooks are present. There ai-e 14 minor hooks. 

 The posterior disc is exceedingly broad, being nearly thrice the width of the 

 rather slender body. The cephalic glands are connected with four pairs of head 

 organs. Four eyes are present. The two limbs of the intestine end blindly and 

 are devoid of caeca. The testis is solid; the cirrus simple. The ovary lies 

 transversely in front of the testis. There is no vagina. 



Foimd on the gills of the freshwater fish, Iherapon umcolor Gunther. 



Type s -p eeies, E. angvstvs J. & T. 



Empleueodiscus angustus, n.sp. (Plate six., figs. 56-60, 63-64.) 



Leng-th about .32 mm.; breadth .05 mm. 



This worm is characterised by the great relative width of the disc, which 

 measures nearly thrice the body breadth. Its armature (PI. xix., fig. 64) is more 

 complex than that of any other member of the Gyrodactyloidea. Four large 

 hooks are present, a dorsal pair with a biramous basal portion, and a more 

 simple slender ventral pair. A complex set of chitinous bai3 lies between these 

 hooks, but does not form a definite articulation with them, serving probably 

 rather to strengthen the disc as a whole. This chitinous apparatus consists of 

 two pairs (a large and a small) of inwardly directed chitin-pieces which articulate 

 with a complexly made intennediate portion. Muscles can be seen inserted at 

 the base of the hooks. Fourteen minute hooks are also present, their distribution 

 being shown in the figure. Four appear to lie on the dorsal side of the disc, 

 while the others are ventral. Two squamodiscs occur, each bearing nine rows of 

 modified "scales." Each disc is also provided with a variable number, generally 

 about thirty, of sharp slender hooks. The clinging disc of the worm is thus 

 armed with as many as eighty hooks. 



The scale-like papillae, characteristic of the Lepidotreminae, are absent only 

 on the head. Of the body-muscles, a well-developed circular, and poorly-developed 

 longitudinal layer could be detected. 



The head organs of this species are very prominent; a large anterior pair 

 and two smaller posterior pairs being present and it appears that the latter are 

 actually protrusible (PI. xix., fig. 60). The cephalic glands supplying them ai-e 

 very small and lie well in front of the eyes, close behind the last pair of 



The mouth lies mid-ventrally, in front of the eyes. A long buccal cavity 

 leads into the pharynx. Lateral to the very short oesophagus is a pair of 

 digestive glands. The forked intestine is devoid of caeca and ends blindly. 



