11 



awl-shaped and pointed ; and the guard (PI. I. fig. 2, 

 C, /3), which is a protuberance situated at the middle 

 third. These hooks are of various sizes, and are 

 received into little sacs or follicles, which are dis- 

 posed in a double row, as are the hooks themselves. 

 These sacs have received the name of hook sacs 

 (Hakentasche ; Kiichenmeister), and, when the Tseniee 

 become old, the hooks are lost ; this loss is therefore 

 considered as a sign of maturity (Von Siebold). As 

 stated above, the cephalic protuberance is imper- 

 forate. At one time this was believed to be the 

 mouth ; this is now shown not to be the case : though 

 whether these parasites are provided with an oval 

 aperture or not, is yet an open question; some au- 

 thors contending that they are supported by imbibition 

 through the skin ; others claiming the probable exist- 

 ence of a mouth, judging from the fact that it has 

 been found in T. serrata and in T. osculata by Leuck- 

 art, and in Dibothrium claviceps by Wagener, in which 

 species it was also supposed not to exist (Weinland). 

 Passing downwards, we arrive at the neck (PL I. fig. 

 2, A), about 6 " in length (Kiichenmeister), slender, 

 slightly depressed, and transversely wrinkled, but not 

 articulated. These wrinkles become more and more 

 marked, and finally become transverse folds, dividing 

 the worm into joints. These joints grow by a con- 

 tinuous pushing from the head and neck, whereby it 

 follows that the joints nearest the head are the young- 

 est (Weinland). They are not matured until they 

 receive the sexual organs (PI. I. fig. 3, A ; and fig. 4), 

 which first appear at the 280th segment, in the me 



