344 • BENEDICT. [Vol. XVI. 



The musculature of the suckers consists of three layers. 

 Beneath the cuticular lining of the suckers is a layer of circular 

 muscles, precisely as in the proglottids (PI. XVI, Fig. 3, m.s). 

 Within these is the principal layer composed of fibers running 

 perpendicularly to the surface for a distance of .065 mm. at 

 the center and gradually decreasing to .04 mm. at the edges. 

 Prominent nuclei are situated in the median zone of this layer 

 (PI. XVI, Fig. 3, tnp). The proximal ends of these fibers are 

 woven in with a second circular layer of considerable thickness, 

 but of loosely arranged fibers. A thin, dense, basement mem- 

 brane covers the inner surface of the sucker. 



In the body the partitions between the proglottids are sheets 

 of muscle fibers, running transversely, with a much smaller 

 number of dorso-ventral strands. 



Nervous System. — In the scolex a thick band of nervous 

 tissue is arranged in a circle, somewhat anterior to the center 

 of the head. From a point on the ring directly beneath the 

 lateral furrow project two branches, one to each adjacent 

 sucker, so that each sucker receives two trunks, which enter 

 the lining membrane at two distinct points (PI. XVI, Fig. 8, 

 n.7'^. The band varies from .02 mm. in breadth, and .01 mm. 

 thick in one specimen, to a thick mass surrounding the pecul- 

 iar spherical bodies described hereafter, and having a thickness 

 nearly twice as great as in the first instance. 



From the scolex two longitudinal trunks run down the 

 lateral margins of the proglottids just within the muscle 

 bundles (PI. XVI, Fig. 16, n.). In many transverse sections it 

 appears as if the nerve sent off at certain places many 

 branches of various sizes ; but until live specimens can be 

 obtained this cannot be proved. In the end of the last pro- 

 glottis the nerve trunks bend toward each other and break 

 into fine spreading fibers. 



Excretory System. — Just behind the suckers in the scolex is 

 a complicated system of rather regularly curving tubes of vary- 

 ing size and connected by curving cross branches. From the 

 outer parts of the ducts smaller branches lead to the exterior 

 and open by excretory pores through the cuticula (PI. XVI, 

 Fig. \\,p.ex). From the scolex eight longitudinal excretory 



