AKT. 6. ANATOMY OF DINOBOTHRIUM LINTON. 7 



ing fact that this localization of subcuticular glands is limited to the 

 posterior half, or two-thirds, of the right side of the ventral surface 

 of the proglottides. The fibers of the longitudinal muscles are fine 

 and arranged in fascicles. 



In a section of a mature proglottis, at a point where the thickness 

 was 0.44 mm., the thickness of the subcuticula was 0.08 ram., and 

 that of the layer of longitudinal muscle fibers O.OG, It should be 

 said in this connection, however, that there is considerable variation 

 in the ratios even of measurements made at different points on the 

 same section. 



No layer of circular muscles could be distinguished in any of the 

 sections, so that all the space within the layer of longitudinal 

 muscles is occupied by parenchyma in the immature segments, by 

 the reproductive organs in mature, and by remnants of reproductive 

 organs and eggs in ripe proglottides. 



The ventral excretory vessels are relatively large as seen in sec- 

 tion, the dorsal are more variable on account of their more tortuous 

 course. 



Male reproductive organs, — The cirrus lies beside the vagina, in 

 some cases a little below the level of the vagina, in others a little 

 above. It is rather short, was not seen everted, is armed with 

 straight, slender spines, measuring about 0.015 mm, in length. The 

 cirrus-pouch is cylindrical, and its walls are rather thin. The vas 

 deferens is voluminous, some of its folds lying beside the inner end 

 of the cirrus-pouch, and extending to the median region of the pro- 

 glottis. The testes are distributed on the dorsal side of the proglottis, 

 from near the margins, and fill more than half of the parenchymatous 

 space on either side of the medianly placed germarium. The volu- 

 minous folds of the vas deferens and those of the vagina and seminal 

 receptacle lie close together towards the median portion of the 

 proglottis. 



Female reproductive organs. — The vagina lies beside the cirrus- 

 pouch, and opens at the common genital pore, which is situated at 

 about the middle, or a little in front of the middle, of the lateral 

 margin of the proglottis. It lies, in the main, parallel with the 

 cirrus-pouch, both being about at right angles to the margin of the 

 proglottis. In some cases it is a little above the level of the middle 

 of the cirrus-pouch, in others a little below that level. The walls 

 of the vagina are thick and glandular. It is somewhat tortuous for 

 a short distance in the neighborhood of the inner end of the cirrus- 

 pouch, and again, as it approaches the median line, it is thrown into 

 numerous capacious folds which constitute the seminal receptacle. 

 At about the median line it turns abruptly towards the posterior, 

 narrows to a slender tube, and enters the germ duct at a short dis- 

 tance back of the bulbous, thick-walled structure which marks the 



