472 REPORT OP COMMISSIONER OP PISH AND FISHERIES. [20] 



is unchanged either by fresh water or alcohol. When placed in fresh 

 water the bothria become profoundly modified. Two distinct forms 

 were observed: in one lot the specimens measuring from 112 to 124""" 

 in length, the breadth of the head is 3.5 mm , its length is 1.5 mm . The 

 bothria are trumpet-shaped, very transparent and delicate, the outer 

 face convex and surrounded by a delicate, narrow, raised border. It 

 is circular except at the anterior edge, where it is broadly indented and 

 interrupted by a circular, opaque disk (the auxiliary acetabulum). 

 (Plate III, Fig. 6.) 



In a second lot, the individuals of which measure from 05 to 250 mm 

 in length, the breadth of the head is about 2 mi ", its length 1.5 mm . (In 

 an active specimen in sea- water the length of the head is about one- 

 half of the breadth.) The rim or border of the bothria is irregular, 

 broken, or ragged in outline, which gives to the head a crisped appear- 

 ance, so as to suggest upon superficial examination the genus Phyllo- 

 bothrium (Plate III, Fig. 5). The auxiliary acetabula are often concealed 

 by the ragged edges of the bothria, but they can be plainly seen in a 

 top view of the head (Plate III, Fig. 15). 



Both the male and female apertures are marginal. It is often very 

 difficult to make out the course of the vagina. By compressing a free 

 proglottis, or better by flattening a proglottis between two glass slips 

 and hardening it while in that position, and afterwards staining and 

 transferring to glycerine or oil of cloves, the topography of the genital 

 apparatus can be made out. At first I was wholly at fault with regard 

 to the position of the vaginal opening, having been misled by the lateral 

 aperture which is usually to be seen in the mature segments and from 

 which the ova are discharged. This aperture resembles the vaginal 

 opening in many of the Dibothrice. It is found only in the posterior 

 segments of the largest specimens and in the free proglottides. It is 

 not always present even in these, as it is not unusual to find a free pro- 

 glottis without the lateral aperture. When such a proglottis is ex- 

 amined its central part will be found to be filled with ova, often to such 

 an extent that the lateral face of the proglottis is swollen in the middle 

 so as to have a convex outline. In this case the lateral aperture may 

 be seen already outlined but closed by a thin membrane, upon the rupt- 

 ure of which the eggs make their escape. The ovaiy is a lobed, glan- 

 dular body lying near the posterior end of the proglottis. The vagina 

 after leaving the ovary follows the median line but a short distance. 

 It bends in a uniform curve towards the margin, and in its outer part 

 lies immediately in front of the penis and very close to it. In the speci- 

 mens which I have examined the course of the vagina as it approached 

 the margin could not be made out until after it was differentiated by 

 staining with carmine. The marginal aperture of the vagina is very 

 small and is situated immediately in front of the peni3. When the lat- 

 ter is retracted the two genital apertures seem to have the same mar- 

 ginal openiug. The penis is long and slender. In some cases it was 



