more or less white sphincter (Moquin-Tandon ; PI. 

 II. fig. 6, A, a). 



When unfolded (PI. II. fig. 6, B), this Cysticercus 

 is seen to possess a head (PL II. fig. 6, B, a), a neck 

 (PI. II. fig. 6, B, b), and then to terminate in a sac 

 filled wkh a fluid containing fat, albumen, and cal- 

 careous matter (Kiichenmeister). This sac is the 

 caudal vesicle (PL II. fig. 6, B, c). In this caudal 

 vesicle, which is identical with the third sac spoken 

 of above,. the parasite is contained when in a folded 

 condition. 



The head and neck are very similar to those of the 

 Tseniae ; and this resemblance had been noticed long 

 before the connection between the two had been estab- 

 lished. The head is furnished with sucking discs (PL 

 II. fig. 6, C, a), from four to six in number, round 

 which the vascular system runs, and afterwards col- 

 lects into two longitudinal canals on each side (Kiich- 

 enmeister) ; and is surmounted by a rostellum or pro- 

 boscis, surrounded by a circlet of hooks varying in 

 number from 22 to 32 (PL II. fig. 6, C, b). This 

 head is colored with a yellowish or blackish brown 

 pigment ; and there are found, round the stem of the 

 hooks, five sacs (Kiichenmeister). 



The neck (PL II. fig. 6, C, c), of varying length, is 

 rugous, as it is in the Taeniae, like them not articu- 

 lated, and contains a few calcareous corpuscles. 



The caudal vesicle (PL II. fig. 6, B, c) is formed of 

 contractile tissue, and contains circular parallel rings. 

 It is homogeneous, destitute of vessels and calcareous 

 corpuscles, and consists of an organic substance be- 



