56 PROCEEDINGS OF THE NATIONAL. MUSEUM. vol.64. 



for about ten sections, that is to about the 16th section from the 

 margin. Sagittal sections show that the proglottis thins a little in 

 the vicinity of the cirrus-pouch. For example, in a sagittal section 

 with maximum breadth, representing the thickness of the proglottis, 

 of 0.25, the thickness at the level of the cirrus-pouch was 0.18, and 

 the diameter of the pouch at this point was 0.14. 



The vagina turns posteriorly near the median line, and enlarges 

 into a relatively spacious seminal receptacle which occupies a median 

 axial position. A slender sperm duct, which lies in a somewhat close 

 and irregular spiral, leads from the seminal receptacle to the germ 

 duct, which is joined later by a single yolk duct. The shell gland 

 appears in the sections as a very compact structure^, granular in its 

 central portion. The anterior border of the two-lobed ovary is about 

 on a level with the posterior angle of the marginal genital notch. 

 Its breadth is about half that of the proglottis, the lengtli about equal 

 to the breadth, and the distance between its posterior border and 

 the posterior end of the proglottis equals approximately the breadth 

 of the ovary. The vitellaria are distributed throughout the proglottis, 

 showing in sections as a layer lying within the muscular layer of the 

 body wall, and continuous, in adult proglottides, in which eggs have 

 just begun to appear, except in the immediate vicinity of the cirrus- 

 pouch. The uterus begins as a slender duct leading from the shell 

 gland, quickly expands into a capacious pouch, is, in earlier proglot- 

 tides, somewhat sacculate on its lateral margins, but in ripe proglot- 

 tides comes to fill practically all the interior in front of the cirrus 

 pouch. 



In mounted material the ova are for the most part collapsed and 

 boat shaped, with length up to 0.04 mm. Two, not collapsed, measured 

 0.039 by 0.028, and 0.042 by 0.028 in the two principal diameters. 



RHYNCHOBOTHRIUM ATTENUATUM Diesinir- 



18976, pp. 805-806, pi. 5, figs. 8-11. 



1900, p. 278. 



1901, p. 448. 

 1911, p. 587. 



Records of this species not heretofore published : 

 Larval stage. 

 Carcharhinus milberti. 



1922, August 5:1, from serous coat of viscera. 



Vulpecula ma7^na.. 



1912, August 7: 2, from serous coat of liver of a 510-centimeter 

 shark, taken at Menemsha Bight, stomach and intestine brought to 

 laboratory by Vinal N. Edwards. The stomach contained only a few 

 vertebrae, lenses and otoliths of fish. These larvae were placed in 



