CESTODA. 837 



PLATE VII. 



T^NIA COENURUS. 



Fig. 1. — Life History. Ovum, six-hooked embryo, Cosimrus cere- 

 hralis (sheep), Toenia cosnurus (dog). 



Fig. 2. — Six-hooked embryo, sui-roimded by shell of ovum, highly 

 magnified. Notice shape of ovum ; the shell consists ot 

 layers, each layer composed of little prisms cemented 

 together. 



Fig. 3. — The non-sexual cystic stage, Coenurus cerebralis. Notice 

 the numerous heads or scolices with which the cyst is 

 provided ; hence the name ccenurus. 



Fig. 4. — Head or scolex magnified 350 diameters. Notice rostel- 

 lum and the crown of hooks, twenty-seven in number 

 (usually twenty-eight), arranged in two rings. Four oval 

 suckers, two being seen through the head. The calca- 

 reous particles are very numerous, and are often mis- 

 taken for ova. 



Fig. 5. — Ttenia cosnurus : a shows the young anterior part of the 

 worm (natural size). A complete worm may have as 

 many as 220 segments, b and c show the segments as 

 they ripen. Observe how the uterus gains in conspi- 

 cuousness as the segments ripen. Notice also the genital 

 pore on the margin of each segment, and their alteration 

 in form as they become older, d. Segment magnified to 

 show the uterus. 



T^NIA ECHINOCOCCUS. 



Fig. 6. — The sexually mature tienia — a. natural size ; b. magnified. 

 Notice the small size of the worm, the three segments, 

 and the head provided with hooks. G. p., genital pore. 



T^NIA CUCUMBRINA. 



Fig. 7. — Head and segments of the sexually mature taenia. 



a. Notice the protrusible rostellum of the head. Only two of 



the four suckers are seen (highly magnified). 



b. Hook attached to the middle of a disc. 



c. Four segments (natural size). Notice the rounded ends, 



giving the segment the appearance of a cucumber ; hence 

 the name cucimierina. Also that each segment is pro- 

 vided with a pair of genital pores (G. p.) 



T^NiA Marginata. 



Fig. 8. — a. The Cysticercus temdcolUs. Notice the round cyst, the 

 head evaginated, and the long thin neck ; hence the 

 name tenuicollis. b, c. Notice the alteration in the 

 form of the segments, d. Head with suckers and hooks. 

 t. Segment magnified, showing uterus. 



