141] . PROTEOCEPHALIDAE—LA RUE 141 



mm. broad by 0.40-0.63 mm. long. The length of the ripe proglottids 

 may exceed the breadth. They measure 0.90-2.08 mm. long by 0.491- 

 1.20 mm. broad. The head (Fig. 1) is very short. It has a slightly 

 rounded apex which is not marked by grooves or furrows. The head is 

 somewhat flattened dorsoventrally, being 0.320 mm. broad at the base 

 of the suckers and about 0.150-0.160 mm. thick. At or slightly above 

 its broadest zone the head bears the four almost spherical suckers which 

 have a maximum diameter of 0.095-0.106 mm. The opening of the 

 sucker measures 0.050-0.060 mm. Tho not measured the sucker cavity 

 is fairly deep. The musculature of the suckers is moderately well 

 developed. 



A fifth sucker is not present in this material, nor did Schneider or 

 Nufer find one. It is replaced by a structure such as was described by 

 the writer for P. filaroides and which was there called an endorgan. 

 This structure is in reality a vestigial sucker. It has no elongated cells, 

 tho Schneider says that he saw such cells, and there is no trace of 

 muscles. In my specimens it is composed of a very few cells of irregu- 

 lar shape surrounded by a membrane that is homologous with a basal 

 membrane in other suckers. This vestigial fifth sucker is situated a few 

 micra below the cuticula and it has no connection with the exterior. It 

 measures 0.020-0.025 mm. This structure does not resemble the fifth 

 sucker of P. percae for it has been shown (Figs. 8, 9, 120) that in P. 

 percae this is a muscular organ which doubtless functions as a sucker. 



The neck is long and broad and thin. Frequently it measures 

 0.225-0.300 mm. or more in breadth while its length varies from 5.0 to 

 7.0 mm. The strobilation is quite evident. The notches between the 

 segments are deep and the angles of the proglottids are somewhat 

 rounded. Many shallow longitudinal folds give the surface of the worm 

 a roughened appearance. The genital aperture is marginal, situated 

 about the middle of the proglottid, and is irregularly alternating. There 

 is no genital papilla. The excretory and nervous systems have not been 

 carefully investigated. The musculature of the strobila is much as 

 Benedict (1900) found it for P. amhloplitis tho the muscles are not as 

 heavily developed. 



The testes (Fig. 49) lie in a single layer in the dorsal region of the 

 medullary parenchyma between the vitellaria and anterior to the ovary. 

 They are closely packed together until many of them are more or less 

 polygonal in shape. They measure 0.063-0.074 mm. long by 0.042-0.063 

 mm. broad and they number from 100 to 120. The vas deferens forms 

 a thick mass of coils extending from the middle of the proglottid to the 

 very short cirrus-pouch. Schneider very well says that the mass of 

 coils of the vas deferens is excentric lying on the side in which the 



