AUT. 21. PARASITES OF SHARKS AND SKATES LINTON. 75 



towards the tips of the other (figs. 103, 104). These rows of stout 

 liooks are flanked on either side with the slender hoolis already men- 

 tioned. Those of one side have broad bases, when seen in outline 

 (fig. 103). The contractile bulbs are slender, and about one- third 

 the length of the neck of the scolex. 



The strobile, in general, is somewhat linear, and rather thin in its 

 dorse- ventral diameter. Its breadth at the junction with the scolex 

 is about 3.5 mm. At a distance of less than 10 mm. from the scolex 

 the breadth has increased to 6 mm. This breadth is maintained to 

 the middle of the length of the strobile. With the formation of 

 adult proglottides the breadth diminishes slightly, the posterior pro- 

 glottides having a maximum breadth of about 3.5 mm. The last 

 five proglottides have a uniform length of 6 mm., and maximum 

 breadth of 3.5 mm. 



First indications of proglottides, in the shape of closely crowded 

 transverse lines, are seen near the scolex, and, at a distance of 8 mm., 

 the segments are distinct with a length of 0.25 mm. The first adult 

 proglottides appear about 70 imii. back of the scolex, where they are 

 a little broader than long. They increase in length gradually, the 

 posterior proglottides being longer than broad, somewhat constricted 

 at their anterior end, and increasing in breadth to near the posterior 

 end. 



The genital apertures are irregularly alternate, and are situated 

 at about the posterior third of tlie lateral margin. None of the cirri 

 were everted. In each case the genital pore was at the center of a 

 depression in the form of a notch with vertical walls. The cirrus- 

 pouch is small, oval, nearly transversely placed. The vas deferens 

 lies at the anterior border of the inner end of the cirrus-pouch and 

 extends a little anteriorly to the median line. In many of the pro- 

 glottides a globular body lay near the inner end of the cirrus-pouch 

 which appears to be a seminal vesicle. Testes could be seen in the 

 earlier adult proglottides, although somewhat masked by the vitel- 

 laria. They fill the interior of the proglottis, are most abundant in 

 front and in the median region bounded by the lateral excretoiy 

 vessels, although a few could be seen lying lateral to the excretory 

 vessels, and lateral to the ovary at the posterior end of the pro- 

 glottis. 



The vagina lies on the posterior border of the cirrus-pouch, and 

 passes toward the median line, thence back to the ovary, which is 

 many lobed, and situated near the posterior end of the proglottis on 

 the median line. 



Sections were not made, and details of structure of shell gland 

 and the complex of vetelline, germ and sperm ducts could not be 

 made out from the mounted segments. The uterus opens on the 

 median line near the anterior end of the proglottis. In earlier adnlt 



