No. 2.] STRUCTURE OF TWO FISH TAPEWORMS. 355 



From the first vitellarian receptacle a duct runs ventrally 

 and expands into a prominent second yolk reservoir (PI, XVI, 

 Fig. 12, vt.r.), which is situated close to the beginning of the 

 ootype. From this reservoir, which is larger than the first, a 

 narrow, heavy-walled duct leads into the ootype. 



As the proglottis nears maturity the dermo-muscular sac 

 begins to get thinner for a short distance in the mid-dorsal 

 line. As the uterus becomes distended with eggs, it pushes 

 up into this portion. With the further growth of the uterus 

 and development of the eggs, the body-wall at this point be- 

 comes thinner and thinner, until it breaks apart and a cleft 

 is formed. Then the pressure on the wall of the uterus at this 

 point causes its rupture and the eggs escape. 



Proteocephalus filicollis Rud. 



The early investigators, Rudolphi ('lO), Dujardin ('45), Diesing 

 ('50), and von Linstow ('78), all described Taenia filicollis and 

 Taenia ocellata as distinct species, as also did Zschokke ('84). 

 The last author, however, added something of the anatomical 

 structure to the details of size and external form given by the 

 older writers. Kraemer ('92) was the first to study by the sec- 

 tion method these two forms, making an exhaustive anatomical 

 and histological investigation, which showed T. filicollis and 

 T. ocellata to be identical. As T. filicollis has the precedence 

 in Rudolphi's synopsis, this name should always apply. Rig- 

 genbach ('96) unaccountably states that ocellata has the prece- 

 dence, although T. filicollis is described in Rudolphi's work ('10) 

 on p. 106, and T. ocellata on p. 108. 



In P. filicollis Kraemer established the presence of a nervous 

 mass in the scolex, and two longitudinal nerve trunks through 

 the body. The excretory system was shown to consist of a net- 

 work of ducts in the scolex and neck, and four longitudinal 

 vessels through the proglottids. He demonstrated the similar- 

 ity of the cuticula with that of other cestodes. The vagina was 

 shown to open in front of the male opening, and to possess at 

 its distal end a sphincter muscle. He established the presence 

 of a bi-lobed ovary in the posterior end of the proglottis and 



