480 REPOET OF COMMISSIONER OF FISH AND FISHERIES. [28] 



and inclose two sides of a triangular space. At the extreme anterior 

 end of each of these secondary sulci is situated one of the four probos- 

 cides. Each bothrium is broadly convex on the posterior border, with 

 often a slight einargination on the posterior edge of each lobe. Each 

 lobe is triangular, the posterior side being the posterior edge of the 

 bothrium, the outer side being the marginal edge of the bothrium, and 

 the inner side being bounded by the median sulcus and one of its 

 branches. The central portion or face of each lobe is sometimes de- 

 pressed, which gives rise to the appearance of a double furrow on each 

 side of the median triangular piece. Posterior edges of bothria thick 

 and fleshy, overlapping the neck. Neck tubular, conical, sometimes 

 slightly swollen back of the head, a little shorter than the bothria, the 

 posterior fourth prolonged into a collar, which incloses the anterior part 

 of the body and its articul&tion with the neck. Proboscides (trypanorynchi 

 Dies.) four, a little shorter than head, armed with numerous hooks 

 arranged in spirals, about eight visible in each spiral ; spirals about 

 0.02 mm apart. Hooks recurved, pointed, broad at base in an antero- 

 posterior direction, very thin from side to side, those near the base of 

 the proboscis shorter- curved and blunter than the others. Proboscis 

 sheaths straight in front, but with a single short spiral curve at the 

 posterior end where they join the contractile bulbs, with one of which 

 each is connected. The four contractile bulbs, which lie side by side in 

 the neck, are about twice as long as broad and about one-half the 

 length of the neck. The distance between the point of articulation be- 

 tween the neck and the body and the posterior end of the contractile 

 bulbs is normally about one-third the length of the latter. 



So far as examined the heads presented the same general outline, 

 with one exception. In the exceptional case noted there is a slight 

 constriction of the bothria where they overlap the neck, at the point 

 which marks the greatest diameter of the head in all the other speci- 

 mens. This imparts to the head a more rounded outline in front than 

 in the others, and a less diameter proportionally at the base of the 

 bothria. 



The body, usually very much attenuated anteriorly, is unjointed for 

 a short distance back of the head. Fine transverse lines soon make 

 their appearance, and shortly afterwards the first segments are formed. 

 The latter are usually much broader than long, and rectangular in out- 

 line. Although they sometimes are lengthened with rounded corners, 

 so as to give to the series of segments a beaded appearance. 



The mature proglottides are always squarish, or rectangular, some, 

 times longer than broad, sometimes broader than long. The male gen- 

 ital openings are marginal, irregularly alternate, always near the an- 

 terior edge of the proglottis. Female genital openings lateral, median 

 dehiscent, apparently not appearing until the proglottides are almost 

 ready to separate. 



Length of strobiles with mature proglottides from 40 mul to 230 mni . 



