36 PROCEEDINGS OF THE NATIONAL MUSEUM vol.70 



1917, January 17.— Two, slender, one with scolex, maximum 

 length 25 mm. 



1917, January 27. — Many fragments, no scoleces; maximum 

 length 25 mm. 



1918, January 8. — Many fragments, two strobiles, longest about 

 24 mm. 



HYMENOLEPIS HAMULACANTHOS, new species 

 Figures 114-126 



Scolex. — Somewhat pyramidal, when the rostellum is extruded; 

 suckers relatively large ; rostellum armed with a circle of 8 hooks, the 

 basal ends of which are thin and claw-like; diameter of scolex, in 

 balsam, 0.25, of sucker 0.13; length of hooks 0.108. 



Strobile. — Anterior end slender ; proglottides begin near the scolex, 

 for the most part broader than long; at the anterior end, Avhere the 

 genitalia first appear, the length is 0.02, the breadth 0.14; near the 

 posterior end, ripe proglottides, in a specimen mounted in balsam, 

 are 0.56 long and 2.8 broad. At intervals there are regions Avhere the 

 breadth is only about three times the length. The proglottides, in 

 the anterior fourth of a strobile measuring 112 mm. in length, are 

 very short and crowded, the lateral margins of the strobile being 

 crenulate. As the proglottides begin to lengthen their posterior 

 diameter becomes greater than the anterior, and the lateral margins 

 of the strobile are serrate. The genital pores are unilateral, near 

 the anterior end of the proglottis, the cirrus and vagina opening near 

 together in the genital cloaca. The cirrus is very long and slender, 

 with a slight bulbous enlargement at the base which is spinose (fig. 

 121). The cirrus-pouch is elongate, somewhat clavate, and extends 

 beyond the poral excretory vessels. Its inner half, or more, functions 

 as a seminal vesicle; sagittal sections show that its walls are formed 

 of longitudinal muscles. It communicates by a short vas deferens 

 with an inner seminal vesicle which extends nearly to the mediiin 

 line, where it turns at nearly right angles and leads to near the pos- 

 terior margin of the proglottis, where it receives vasa efferentia from 

 the testes. There are three testes, one on the poral, two on the anti- 

 poral side. In maturing proglottides the testes are profoundly lobcd 

 (fig. 117). The vagina opens on the ventral side of the cirrus. For a 

 short distance it has rather thick muscular walls, in a series of sagittal 

 sections seen to be a sphincter muscle; it then narrows to a slender 

 tube which lies on the ventral side of the cirrus-pouch for about half 

 the length of the latter. It there expands into a capacious seminal 

 receptacle, which sends a short, and rather broad duct to the vicinity 

 of the shell-gland. The ovary is on the median line, and like the 



