138 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 83 



320/A in diameter. Head sharply constricted behind suckers. Neck 

 long, segmentation beginning to show faintly at 5 to 9 mm from 

 anterior end, with minimum width of 360/* to 450)Lt. Proglottids at 

 first much broader than long, but relative length rapidly increasing 

 until, at a distance of 4 cm from head, they may be approximately 

 square if in an uncontracted state. Even mature segments 10 or 

 12 cm from head vary greatly in measurements according to state 

 of contraction, some being broader than long (1.8 mm broad by 1.2 

 mm long) , others longer than broad (1.2 mm broad b}^ 2.1 mm long) . 

 Ripe segments longer than broad, varying in breadth from about 

 1.2 to 1.5 mm and in length from 2.8 to 4.7 mm. 



Genital pores marginal, without papillae, irregularly alternating, 

 about one-fifth to two-ninths length of segment from anterior end. 

 Testes very numerous, about 200 to 22o or more, GO/a in diameter, 

 arranged almost all in one plane, and filling in greater part of space 

 between viteilaria anterior to ovary, although soon crowded out 

 of middle portion of segment posterior to cirrus by developing uterus 

 (pi. 9, fig. 1). Vas deferens forms dense mass of coils lying between 

 cirrus pouch and median line of proglottid. Cirrus pouch roughly 

 three-eighths width of segment, measuring about 480/x to 580/x in 

 length by 260/1 to 325/<, in diameter. Retracted cirrus bent upon 

 itself in pouch; ejaculatory duct capable of great distention, which 

 makes the walls appear thin instead of thick and muscular (pi. 8, 

 fig. 8, A). Everted cirrus about 600/x to 650/x long, with bulblike 

 enlargement of proximal half; diameter through bulb about 180/i 

 (pL8,fig.8,B). _ , 



Vagina opens anterior to cirrus and lies close along anterior wall 

 of latter. It is provided with an elongated muscular sphincter, 

 somewhat reminiscent of that of P. mnbloplitis^ extending from gen- 

 ital pore to about half length of cirrus pouch. Musculature not 

 nearly so thick as in P. amblopJitis^ thickest near middle of its 

 length and gradually disappearing instead of ending abruptly as in 

 amhloplitis (pi. 8, fig. 8; pi. 9, fig. 1). Wliole vagina, including part 

 with muscular wall, may be greatly distended, although the sphincter 

 causes a slight constriction in it (pi. 8, fig. 8, A). In young mature 

 segments vagina, after reaching middle of proglottid, passes almost 

 straight posteriorly to ovary, although in older proglottids it has a 

 few kinks (pi. 9, fig. 1). Over bridge of ovary vagina has slight 

 club-shaped enlargement from which lower vagina emerges and 

 after one or two loops enters oviduct near middle of its length (pi. 9, 

 fig. 2). Oviduct originates in oocapt attached to bridge of ovary. 

 Just before entering ootype oviduct is joined by a conniion vitelline 

 duct, which has a reservoirlikc enlargement before it branches to go 

 to opposite sides of segment. Shell gland surrounding ootype an 



