4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.. 61, 



straight, or, in some cases, slightly sinuous, until a short distance in 

 front of the ovary, where it forms a close spiral and functions as a 

 seminal receptacle. 



The ovary lies near the posterior end of the proglottis, and con- 

 sists of two fan-shaped divisions, symmetrically placed with refer- 

 ence to the median line. Each half is made up of numerous tubular 

 or long-pyriform lobules. The two divisions are connected by a 

 common transverse portion at the mid line. The shell gland lies 

 on the mid line behind the transverse connecting portion of the 

 ovary and between the two divisions, and is thus practically sur- 

 rounded by the ovary. The short germ duct begins with a muscular, 

 funnel-like enlargement (ootype), is soon joined by the sperm duct, 

 and a little later by the single yolk duct. The common duct now 

 enters the shell gland, from which it emerges as the oviduct which 

 passes ventrad and shortly expands into the uterus. The main yolk 

 duct is short, and is formed by the meeting of tAvo ducts, one from 

 either side of the proglottis (fig. 7). The vitellaria are distributed 

 mainly along the lateral regions of the proglottis, but also extend 

 more or less mediad so as to overlap the testes. They begin near 

 the anterior end of the proglottis, anterior to the testes, and con- 

 tinue to the posterior end. In mature proglottides, in which eggs 

 have not appeared, the vitellaria are quite dense, glandular organs. 

 In joints in which there are considerable numbers of eggs in the 

 uterus, the vitellaria appear as slender, short, string-like mas.ses of 

 yolk cells. This condition begins at the anterior end of the pro- 

 glottis and progresses toward the posterior end (fig. 8). 



The uterus lies along the median line on the ventral side. Figure 

 6 shows it in section in a mature proglottis which had not yet begun 

 to form eggs. As the segment ripens the uterus becomes greatly en- 

 larged, somewhat sacculate, and ultimately comes to occupy prac- 

 tically all of the interior of the proglottis. The ova are small, and 

 have thin shells. In all of my mounted material the shells have col- 

 lapsed, so that the ova have very irregular, and more or less angular, 

 outlines. The diameter is about 0.02 mm. 



Eggs are discharged by way of a relatively large, longitudinal 

 opening, which appears by dehiscence, on the ventral side of ripe 

 proglottides. 



2. NOTES ON HABITAT, DISTRIBUTION, ETC. 



A. Adult stage. 



1. CARCHARODON CARCHAP.IAS. 



The type (Cat. No. 7631, U.S.N.M.) was collected on June 20, 

 1903, by Vinal N. Edwards at Woods Hole, Massachusetts, from the 

 stomach of a maneater shark. No food notes accompanied the speci- 



