234 G. A. aud W. G. MacCallum, 



decrease agaiii to a very small size at the posterior tip. Their 

 more intimate structure may be described later. 



The skin of tlie body in general is thin, smooth and unarraed. 

 At the taperingf anterior end there is the mouth opening- guarded 

 on each side by a flattened rounded sucker measuring 0,12 X 0,16- 

 Between and behind these can be seen the small pharynx, a short 

 way behind which is the genital pore in the median ventral line. 

 The body contains much scattered pigment, and its lateral portions 

 are occupied, from the level of the foot to that of the genital pore 

 by abundant masses of vitellariiim. The intestine is practieally in- 

 visible in the anterior part -of the body bnt it extends into the foot 

 and sends out branching coeca filled with blackish material between 

 the suckers. In the space left between the marginal masses of vitel- 

 larium, one can see the lobules of the testis and count about a 

 hundred of these lobules. In front of the festes is the large coiled 

 ovary with its conspicuous connection with the vitellarian ducts. 



Little more can be easily made out from the study of the whole 

 worm except the character of the egg which Stands out very sharply 

 through its yellow color and high refractive power. This Single 

 egg is elliptical with anterior and posterior prolongations. The 

 posterior one is a relatively short rod with a double recurved anchor 

 like hook at the end ; the anterior is a long extremely fine whiplash 

 like filament which extends out through the genital pore and waves 

 about freely outside the body of the worm. 



Sagittal sections were made to determine the structure of the 

 worm and their study shows the following: 



At the anterior extremity there is a wide mouth, opening, under 

 an overhanging lip, into a cavity, on each side of which there is 

 placed one of the anterior suckers. These are imperforate and do 

 not open to the outside at all, but like cheek pouches, their cavity 

 looks into the sides of the mouth cavity which is quite wide and 

 sacculated posteriorly. Into it projects the small pharynx which is 

 by no means a strong muscular structure but composed of cells with 

 large round nuclei. Externally it has a delicate layer of circular 

 muscle fibres. Its central lumen is extremely narrow and it is 

 difficult to see its opening into the wide Oesophagus which ventrally 

 projects some distance in front of it. Thus the pharynx comes to 

 stand out quite free in the prepharynx and to lie as it were on the 

 dorsal surface of the Oesophagus. Muscle bundles run up to it from 

 points quite far back in the body wall. 



