[35] NOTES ON ENTOZOA OF MARINE FISHES. 753 



The testis, in the postero-mediau segments, is represented by several 

 large granular masses situated towards the marginal portions of the 

 internal cavity. A convoluted tube, lying at the base of the cirrus 

 bulb and communicating with it, is evidently the vas-defereus. This 

 tube appears finely fibrous as if filled with fine filamentary particles. I 

 have noticed a similar appearance in some living cestods in which case 

 the presence of spermatozoa was demonstrated. 



I was not able to fix the position of the vagina to my entire satisfac- 

 tion. In a few sections the cut end of a tube was observed near the 

 cirrus bulb and on its posterior side. This, if it represent the vagina, 

 would indicate that that organ opens behind the cirrus. Olsson, how- 

 ever, figures the vagina of D. rugosum, as opening anterior to the cir- 

 rus. I may be able to clear up this matter by further examination of 

 the material at my disposal. 



Musculature of posterior and posteromedian segments. — In passing 

 from the exterior of the muscular wall of a posterior segment to the in- 

 terior, one finds first a thin cuticle, next a thick, dense granular layer, 

 in which there are very numerous radial fibers which in turn pene- 

 trate the third or inner layer. This third layer consists for the most 

 part of very large longitudinal fibers arranged in fascicles. The fasci- 

 cles, in transverse sections, are somewhat triangular, with the apex of 

 the triangle directed toward the exterior. The triangular transverse 

 section of one of these fascicles measured .05 mm in length, .03 mm at base, 

 and .013 mm at the apex. These fascicles are largest along the lateral 

 sides, and smaller but more numerous at the margins. Iu longitudinal 

 sections they appear as broad parallel bands of muscular fibers, the in- 

 dividual fibers of which are about .002 mm in diameter. 



The reproductive organs are irregularly alternate and open on the 

 margin of the segment near its anterior edge. In the mature segments 

 only the male organ could be made out. The cirrus was retracted and 

 lay in a slender pouch. This pouch lay wholly in the muscular wall 

 with its base near the interior limit of the wall and its apex at about the 

 limit between the outer granular layer and the inner layer of muscular 

 fasciculi. 



The musculature of the postero-median segments was plainly shown 

 in the sections, and some additional data were obtained. The parts are 

 an outer, dense granular layer with fine radiating fibers. On the inner 

 side of this layer is the layer of longitudinal fasciculi. The latter are 

 really immersed in the granular layer. Transverse sections of these 

 bundles are oblong, usually narrowing a little toward the exterior end, 

 occupying a radial position. The largest lateral ones are fully .08 mm 

 long and .027 mm broad. They are separated from each other by spaces 

 about as wide as their own breadth, and filled with granular and fibrous 

 tissue, in which radiating fibers predominate. On the inner side of the 

 layer of longitudinal fibers is a thin layer of fine circular fibers which 

 H. Mis. 133 48 



