Bi' T. HARVEY JOHNSTON AND 0. W. TIEGS. 105 



the vesieula seminalis is rather smaller than in L. therapon. In some individuals 

 It is almost free from sperms, in others much dilated, the dilatation taking place 

 in a ehaxaeteristie manner resulting in the formation of a strongly lobed struc- 

 ture. The prostate glands are often very prominent. The cirrus is quite similar 

 to that of L. therapon. 



The female reproductive organs are like those of the last species. There is 

 a marked development of the vitellaria — even more so than in L. therapon — so 

 strongly that in some forms none of the other internal structures are visible 

 through it. In general disposition the yolk system is, in other respects, the 

 same as that of L. therapon. 



The egg measures .076 mm. by .048 mm., its spine being slightly longer 

 than that of the last species. 



Found on the gills of Therapon hilU Castelnau, from the Thomson River at 

 Longreach, Central Queensland. 



Lepidotrema fuliginosum, n.sp. (Plate xyi., fig. 44; xvii., figs. 50, 51.) 



Length .64 — .75 mm., breadth .14 — .16 mm. This species closely resembles 

 the other species of the genus. The distinctions most easily observed are in the 

 disposition of the minor hooks on the disc and in the structure of the repro- 

 ductive organs. The arrangement of the minor hooks is clearly seen in the 

 figure (PI. xvi., fig. 44), and differs from those already described in having one 

 small hook situated between each pair of supporting cross-bars. 



Even in full-grown adults the testis is large and distinct, though the size 

 of the vesieula seminalis indicates that the male gland has andergone consider- 

 able diminution. The greater part of the vas deferens is dilated into an im- 

 mense vesieula which travels forward on the right side of the body nearly as 

 far as the end of the penis, then, passing over to the left side, bends back again 

 and communicates by a rather long vas deferens with the penis. The latter 

 closely resembles that of the two previously described species. Two prostate 

 glands are present but not very large. 



The vagina is even larger than in the two preceding species. In one rather 

 fortunate preparation the vagina could be seen opening into the ootype a very 

 short distance in front of the opening of the two transverse vitelline ducts 

 (PL xvii., fig. 51). Shell-glands were not recognised. The oviduct is remark- 

 able in that it is highly dilated in its mid-region and is lined by a highly re- 

 fractive cuticle, evidently of a chitinous nature. It opens ventrally on the left 

 side immediately behind the opening of the vagina. 



The egg, which measures .064 mm. by .048 mm., resembles that of the other 

 species of the genus. 



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

 River at Longxeach, Central Queensland. 



16. Subgenus Flabellodiscus, n. subgen. 



Lepidotreminae. In external appearance this subgenus closely resembles 

 Lepidotrema, but the organisation of the reproductive system is considerably 

 simpler. The penis is a simple chitinous tube, the twisted flange, so charac- 

 teristic of Lepidotrema, being quite absent. The vagina which is bent once upon 

 itself, is longer than, but not so thick-walled as in the genus mentioned. The 

 testis lies above this more anterior part of the ovary and is rather small in 

 the adult. The vesieula seminalis is exceedingly large. 



Type species, Lepidotrema (Flabellodiscus) simplex J. & T. 



Found, so far, only on the gills of Therapon fuliginosus Macleay. 



