786 REPOKT OF COMMISSIONER OF FISH AND FISHERIES. [68] 



The walls of the mature proglottides are very thin. They consist of 

 an outer cuticular layer and an inner granulo-mnscular layer. The 

 muscular fibers in this layer are very inconspicuous. 



The small amount of material at my disposal has prevented me from 

 making as thorough examination as the importance of the subject de- 

 mands. 



Anatomy ofproylottides.Th& cirrus is exceedingly long and slender 

 and emerges from a point a little in front of the middle of the margin. 

 The original opening is a little in front of the cirrus. Both sexual 

 organs have a common marginal cloaca which has a thickened muscular 

 border. 



The cirrus bulb, when the cirrus is retracted, is oblong, about .28 mm 

 in diameter and .6 ram in length, and lies at nearly right angles to the 

 margin. The vas defereus is a very voluminous tube which lies near 

 the center of the segment at the base of the cirrus bulb. Some convolu- 

 tions of this organ in one section were found to be .14 mm in diameter, 

 or equal to one-half the diameter of the cirrus bulb. The vas defereus 

 in this case was filled with spermatozoa. 



In those segments which immediately precede the ripe proglottides, 

 the anterior part, and indeed the greater part of the interior of the seg- 

 ment, is filled with granular, globular masses from .070 to .08G mm in di- 

 ameter. These were found in longitudinal sections of segments, to be 

 arranged in racemose clusters on branches which are transverse to the 

 axis of the segment. These granular masses evidently represent the 

 testes, and the branches on which they rest, ducts which communicate 

 ultimately with the vas deferens. 



Beginning at its exterior end in front of the cirrus at the margin of 

 the segment, the vagina, a tube about .06 nim in diameter, passes in front 

 of the cirrus bulb, and in front of and a little to one side of the vas 

 deferens, to the median line of the segment. It there turns abruptly 

 and follows the median line back to the posterior edge of the segment, 

 where it communicates with the ovary. The latter organ is near the 

 posterior edge of the segment. It consists of two lobes which lie sym- 

 metrically on either side of the median line. It is made up of a mass 

 of rounded cells, some of which were found to be nucleated and were 

 apparently unfertilized ova. The diameter of the irregular non-nuclear 

 masses was about .013 miu . That of the nucleated masses, which had 

 apparently left the ovary and were in the vicinity of the shell gland, 

 was about .01G lum . An organ which I take to be the shell gland lies 

 midway between the two lobes of the ovary, is spherical in shape and 

 about .09 mm in diameter. It appears to be a somewhat convoluted tube 

 which connects in front with the vagina and also apparently with a] 

 median groove or cleft on the face of the proglottis. Posteriorly it- 

 connects with an irregular mass which I take to be the vitelline gland. 

 This, when magnified thirty or forty linear diameters, in a section 

 etained with carmine, appeared as an irregular, slightly striated gland- , 



