26 BULLETIN 69, UNITED STATES NATIONAL MUSEUM. 



Internal anatomy. 



Nervous system. — The lateral longitudinal nerves (fig. 18, I. n.) 

 are large and well developed, located in the lateral portions of the 

 segment inside the inner layer of longitudinal muscles. 



Musculature. — The longitudinal muscles (fig. 18) are arranged in 

 numerous small bundles disposed in two layers close together, and a 

 considerable distance from the surface of the segment. Dorsoventral 



fibers are numerous. Trans- 

 verse fibers are compara- 

 tively few, in relation with 

 the outer and inner sides of 

 the inner longitudinal mus- 

 cles which they cross at 

 right angles. 



Excretory system. — The 

 excretory system is well de- 

 veloped. The dorsal (fig. 

 18, (I. ex.) and ventral ca- 

 nals (fig. 18, r. ex.) are 

 located a considerable dis- 

 tance mediad from the lat- 

 eral nerves. The ventral 

 canal is much the larger, 

 measuring in places 80ju, in 

 diameter, whereas the dor- 

 sal canal measures less than 

 8/i,. The ventral canals are 

 connected by a transverse 

 canal in the posterior por- 

 tion of each segment, and 

 also send off anastomosing 

 branches which run among 

 the various organs of the 

 Fig. is. — rhabdometea NnLLicoLLis : heab and segment and also form a 



ANTERIOR PORTION OF STROBILA. ' i • i 



plexus, which extends later- 

 ally on each side of the segment as far as the lateral longitudinal nerve. 



The vagina and cirrus pouch pass between the dorsal and A^entral 

 excretory canals and dorsal of the lateral nerve. 



Male reproductive organs. — The testicles (figs. 17, 18, 20, t.) are 

 about 60 in number, arranged in two layers in the middle field, in 

 the posterior portion of the segment. They measure from 80 to 

 100|U, in diameter when fully developed. The mass of testicles is 

 hollowed out in front, and this depression is occupied by the female 



lOQu.. 



