BY J. P. HILL. 51 



broader at the anterior end, in which the head lies inverted, and 

 tapering to a blunt rounded posterior end. They varied somewhat 

 in size, the largest measuring 3 mm. in length and 2 ram. in thick- 

 ness at the broader anterior end, while the smallest were l'5mm. 

 in length and 1 mm. in thickness, exactly half the size of the 

 largest. When examined under compression the Cysticercus is 

 seen to possess numerous close-set calcareous corpuscles, uniformly 

 distributed over the bo:ly. They are mostly in the form of short 

 rods with rounded ends, measuring in greatest length -04 mm. ; 

 others have a more oval or rounded outline. At the broad end 

 tl)e head lies invaginated. It is pro%'ided with four large suckers 

 whose cavities communicate with the cavity of invagination of the 

 head. Hooks are altogether absent, but at the bottom of the 

 invagination cavity of the head, situated centrally in what will in 

 the everted condition form the apex of the head, is a small rounded 

 body, representing a rudimentary frontal sucker (Fig. 2, /. s.). 

 As the head was not readily everted in water, I have not been 

 able to examine a completely everted Cysticercus. This is the 

 more to be regretted, for in the everted condition the relations of 

 the frontal sucker could have been more easily made out. It 

 appears from the examination of preserved specimens that the 

 suckers can be protruded separately. Fig. 2 represents a nearly 

 median longitudinal section through such a Cysticercus with 

 partially evaginated head, the knob-like mass projecting at the 

 anterior end being one of the protruded suckers in section. In 

 this section the invagination cavity appears as a wide opening, 

 but transver.se sections of a Cysticercus with the head fully 

 inverted show that it is comparatively narrow and lined by cuticle 

 continuous with the external cuticle of the body. It is filled up 

 with a granular deeply staining material which is apparently 

 derived from the coagulated fluid which surrounds the Cysti- 

 cercus. Fig. 3 represents a section through the inverted head 

 of a Cysticercus at the level of the suckers. Their walls are 

 composed of numerous small radially elongated cells and their 

 cavities open into the invagination cavity. The ground tissue 

 immediately surrounding the suckers is seen to be disposed in a 



