213] PROTEOCEPHALIDAE—LA RUE 213 



uniform diameter from base to tip. The cirrus-pouch is weakly muscled. 

 Its length is about 0.22 mm. and its breadth about 0.11 mm., being 

 broadest at its inner end. 



The vagina (Fig. 105) always lies anterior to the cirrus-pouch and 

 does not cross the latter. There are no coils of vagina anterior to the 

 interovarial space. A weak sphincter vaginae and a small receptacu- 

 lum seminis are present. The lobes of the ovary are thin and somewhat 

 alate in shape. They are made up of anastomosing tubules. The organs 

 (Fig. 104) of the interovarial space are typical of the genus. Vitelline 

 follicles are large and are arranged in the lateral fields as in the other 

 members of the group. The uterus in mature proglottids is a median 

 tube. From this tube there arise both lateral and ventral diverticula 

 after the manner described by La Rue (1909:33-37). The lateral 

 diverticula in fully ripe proglottids extend to the vitellaria which by 

 this time have degenerated to a large extent. They number from 25 to 35 

 on either side. The ventral diverticula number about 8-12. These are 

 short and usually pointed. In time they pierce the ventral body wall 

 forming the uterine pores. The ventral body wall now gives way along 

 this line of perforations thus causing a rift which extends from one 

 end of the proglottid to the other. Through this rift the eggs are dis- 

 charged. The eggs are covered with three membranes of the character 

 usual to the group. The outer thin and hyaline membrane varies in 

 diameter from 0.035 to 0.10 mm. This variation is due in part to the fact 

 that when it comes in contact with the water the outer membrane 

 swells up greatly. The second membrane is thick and granular, about 

 0.030 mm. in diameter. The inner membrane which closely invests the 

 embryo is thin. The six-hooked embryo measures about 0.021 mm. in 

 diameter. The larval form of this cestode is frequently found encysted 

 in the abdominal viscera and body muscles of the host, Amblystoma 

 tigrinum. They have also been found free in the body cavity of the 

 same host. As yet they have not been found in an invertebrate host. 



Altho this species shows marked similarities with some of the spe- 

 cies oF cestodes infesting snakes it most nearly resembles Ophiotaenia 

 lonnbergii (Fuhrmann) which infests the amphibian, Nechirus maculo- 

 sus Raf. It differs from this species in size relations, in the character 

 of the excretory vessels, and in the relations of the cirrus-pouch to the 

 vagina. There are some minor points in which the two species from 

 the amphibia differ from the species infesting snakes but as yet charac- 

 ters have not been found by which they can be separated from the 

 genus Ophiotaenia. These two species certainly do not belong with the 

 genus Proteocephalus. 



