102 NEW GYBODACTTLOID TREMATODES PEOM AUSTEALIAN FISHES, 



D. a. Disc much broader than body, squamodisc provided with very numerous 



(about 25 to 30) accessory hooks Empleurodiscus. 



b. Disc with only about eleven such hooks, disc not as broad as body . . . . E. 



E. a. Cirrus a rather simple structure Flahellodiscus. 



b. Cirrus very long, and showing a remarkable complexity of structure 



Lepidotrema. 

 15. Lepidotrema, n.gen. 



Lepidotreminae. The members of this genus are characterised by the pre- 

 sence of about eleven rows of scales on each of the two sucker-like organs of the 

 disc, together with a row of generally about nine hooks on each, arranged like 

 a spread fan. Fourteen minor hooks are scattered over the disc. The large 

 hooks of the disc ai-e supported by four powei-ful chitinous bars imbedded in 

 the substance of the disc. 



The penis is exceedingly complex. The testis is more or less degenerate 

 in the adult, the sperms being stored in an immensely dilated vesieula seminalis. 

 The va.gina is extraordinaiily large. 



Found, so far, only on the gills of freshwater fishes belonging to the 

 genus Therapon. 



Type species, L. therapon J. & T. 



Lepidotrema therapon^ n.sp. (Plate sv., figs. 35-37; xvi., figs. 38-42; xvii., 

 figs. 45-49.) 



Length of adult .5 to .77 mm. ; breadth .19 mm. The body is covered with 

 minute scale-like papillae, veiy minute anteriorly but increasing in size towards 

 the posterior end of the worm. 



The disc (PI. xvi., fig. 40, a-f) is provided with an exceedingly powerful 

 clinging apparatus. In the living condition the true posterior end of the disc 

 is turned ventrally, i.e- the true dorsal surface of the disc is turned backward. 

 Four large hooks are present. The ventral pair (PI. x\'i., fig. 40, c) are slender, 

 and strongly hooked, and articulate basally each with the end of a chitinou,^ 

 bar which rans towards the centre of the disc, but does not quite reach its 

 fellow. These two bars articulate at their inner ends with a much smaller 

 curved piece of chitin which can be observed only by compressing the disc, its 

 plane being vertical to that of the chitinous bars (PL xvi., fig. 40, e). Each of 

 these bars is also provided on its outer half with a strong ring-shaped chitinous 

 projection. The dorsal pair of hooks have a biramous basal portion, the two 

 limbs or roots being united by a strong membrane. The anterior (ventral) 

 limbs articulate with the chitinous bars which also give support to the ventral 

 hooks, but the postea-ior limb has no such chitinous support. Two other in- 

 wardly-directed bars of chitin are also present, articulating with the more dorsal 

 pair. They do not quite reach each other, but a slightly curved piece of chitin 

 similar to and at right angles with the one already described, connects them. 

 Fourteen minor hooks are also present, their disposition being indicated in PI. 

 xvi., fig. 42. 



The dorsal and ventral surfaces of the disc (posterior and anterior in the 

 attached animal) each bear, towards their proximal ends, a remarkable sucker- 

 shaped disc, consisting of blunt teeth arranged in eleven curved rows which 

 radiate outward from a point at the proximal end of the disc (PI. xvi., fig. 40, /). 

 In close eoimeetion with each of these discs are a number of hooks, varying from 

 seven to eleven, connected by a membrane and spread out like a fan. The rows 

 of blunt teeth, and probably also the hooks, are to be regarded as modifications 



