Introduction to Animal Morphology. 1 69 



■second day of freedom, and the body lengthens, and 

 shows transverse lines, deepening into joints. 



There are about 265 species, divided into seven families. 



I . Taeniidae — worms of many metameres ; head with four 

 suckers (Fig. 23,6); sex openings usually marginal. Gymno- 

 taeniae have no rostellum nor hooks, and inhabit herbivorous 

 Mammals, Man, Amphibians, and Teleostean fishes. G. medio- 

 canellata (Fig. 23, B), with a black ring round each sucker, 

 dichotomous uterine pouches and oval eggs is a common human 

 parasite in this country, Siberia, Abyssinia, &c., and some- 

 times is 1200 jointed. G. perfoliata and plicata occur in the 

 'horse. G. dispar in frogs. G. pectinata in hares. Echino- 

 taenia has a rostellum and 1-4 circlets of hooks, and is para- 

 sitic in Carnivores and Omnivores, Man, &c, E. solium, the 

 common tape-worm of Western Europe, has two alternating 

 circlets, one of larger, one of shorter hooks, twenty-six in all, 

 each with a short process at its root, and often black hook 

 follicles ; the uterine follicles are dendritic, and contain 

 spheroidal ova ; its larval stage (Cysticercus cellulosae) is the 

 parasite of measly pork. E. echinococcus, of the dog, rarely 

 in Man (Iceland), consists only of 3-4 metameres, and has a 

 rostellum ; its scolex is the hydatid of the human liver 

 (Echinococcus hominis). E. crassiceps, of the fox, develops 

 from Cysticercus longicollis of the field-mouse. E. elliptica, 

 of the cat, once found in a child, has double sex-organs in 

 each proglottis. E. acanthotrias is only known in its scolex 

 stage as a human parasite with three rows of hooks. E. 

 platycoUis is developed from the human C. turbinatus {Kober). 

 E. nana, found in an Egyptian boy, has an oval rostellum 

 with one row of hooks. E. marginata, of the dog and wolf, 

 rarely in Man, develops from C. tenuicollis of ruminants 

 and swine. E. flavo-punctata, named from the colour of the 

 seminal vesicle when full, was once found in Man. E. ser- 

 rata, of the dog, from C. pisiformis, of the hare ; E. crassi- 

 collis, of the cat, from C. fasciolaris, of the rat and mouse. 

 E. coenurus, with a rostellum and two rows of hooks, in 

 dogs, develops from Coenurus cerebralis of the brain of 

 sheep, which produces the disease known as the " staggers." 



