219] PROTEOCEPHALIDAE—LA RUE 219 



This cestode is thin and slender. Its observed length varies from 

 75-250 mm. and its maximum breadth is not over 1 mm. The segmenta- 

 tion is distinct in the posterior region. The single proglottids are thin, 

 and somewhat translucent. The first proglottids are broader than long 

 and their boundaries between segments are not distinct. More mature 

 proglottids are nearly quadrate while ripe proglottids are longer than 

 broad. The length of ripe proglottids may be as much as 2.0 mm. and 

 the breadth 0.33-0.50 mm. The last proglottids are easily detached 

 from the chain. The head is small and not clearly set oif from the 

 neck. It is unarmed, rounded somewhat but not spherical ; its diameter 

 is 0.24-0.25 mm. It bears four circular suckers which have a deep cavity 

 and a thick muscular wall. The diameter of the suckers varies from 

 0.120 to 0.150 mm. There is no rostellum and no fifth sucker. The neck 

 is seven or eight times as long as the head. Cuticula, musculature, 

 nervous system and excretory system are very similar in arrangement 

 and character to the same systems in other species of the genus. 



The early developing sex organs may be seen in quadrate proglot- 

 tids. The genital aperture lies somewhat anterior to the middle of the 

 margin of the segment and it irregularly alternates from right to left. 

 Schwarz's figure of the ripe proglottid showing the main features of 

 the reproductive systems is reproduced (Fig. 195). The testes lie in 

 two fields between the vitellaria, thus leaving the median zone of the 

 proglottid free of them. They number 80-100 and measure 0.042 mm. 

 The vas deferens forms a thick heavy coil extending from the cirrus- 

 pouch even past the middle of the proglottid. Within the cirrus-pouch 

 there is a very complicated mass of coils of ductus ejaculatorius. This 

 is much more highly developed than in any other known species of 

 Ophiotaenia. The cirrus when protruded is heavy at the base, more 

 slender at the tip and about 0.200-0.210 mm. long. In preparations 

 where it was incompletely protruded it measured 0.108 mm. long. The 

 cirrus-pouch is 0.265-0.280 mm. long. In quadrate and oblong proglot- 

 tids its length goes into the proglottid breadth from 3 to 3.5 times. 



The vagina opens into the common genital pore. It may lie either 

 anterior or posterior to the cirrus-pouch. In 12 out of 18 proglottids 

 examined by the writer the vagina had a posterior position. At the 

 opening of the vagina a sphincter of good size is present. The course 

 of the vagina is nearly direct to the middle of the segment, frequently 

 crossing the inner end of the cirrus-pouch or even lying above the cirrus- 

 pouch for its full length. From the middle of the segment its course is 

 directly posteriad with sometimes a single loose coil just above or ante- 

 rior to the ovaries. In the interovarial space are the usual coils of the 

 vagina, oviduct, uterine passage, and unpaired vitelline duct; here also 



