250 Gr. A. and W. G. MacCallum, 



gland. This tube is quite narrow and extends far back dorsally to 

 the testes into the regiou of tlie abundant uterin e coils. We have 

 tried in vain to trace it to an opening on the surface of the body, 

 but even so one can hardly interpret it in any way except as a 

 Laurer's canal. 



While suiTOunded by a mass of large cells which presumably 

 constitute the shell gland, the corabined oviduct and Laukee's canal 

 receives a duct formed by the union of the canals from the lateral 

 vitellaria. As they unite, these two vitellarian canals form a rather 

 large reservoir from which the narrower Channel runs further into 

 the Shell gland. The resulting duct gives off a coiled elongated 

 sac like diverticulum or receptaculum seminis which is filled with 

 spermatozoa. It then passes backward and widens to become the 

 Uterus which penetrates the muscular partition which in this poste- 

 rior region is much frayed out, and reaches the dorsal part of the 

 body. After many coils on its wa}^, it passes forward to open at 

 the ventral genital pore in front of the ventral disc. The vitellarium 

 is in the form of small compact lobules ranged rather closely 

 together in lines along the sides of the body just dorsal to 

 the muscular partition and therefore in the angle which this 

 forms with the body wall. The ducts perforate this partition 

 to reach the oviduct, The eggs are elliptical and measure 

 0,07X0,04 mm. 



The systematic position of this worm is difficult to establish 

 with certainty. It is probably the same as that described by Linton 

 from the same fish (Trachmotus) and labelled Aspidogaster ringens, 

 but his descriptions are extrem ely meager and it is hardly possible 

 to be quite sure. He himself named it Aspidogaster with some 

 hesitation on account of the inconstancy and frequent absence of 

 the median ridge on the ventral disc. Apparently the structure of 

 that disc changes as the worm grows older and larger and that 

 may account for the number of grooves and marginal suckers which 

 he describes, a number greater than we find (forty-two whereas we 

 find thirty-six). Nevertheless the resemblance is so close as far as 

 one can judge that we feel that this worm must be assigned to that 

 specific name. 



