24 
of hooks; in exceptional cases rostellumis developed into an apical sucker, the arma- 
ture hooks) becoming lost. Genital pores irregularly alternate. Testicles usually 
very numerous, in lateral portions of median field. Ovary, shell gland, and vitello- 
gene gland in distal half of middle zone; uterus with median stem, which develops 
lateral branches; the latter afterwards suppress the genital glands. Of the four 
longitudinal excretory canals, usually only the ventral remain visible in the gravid 
segments. Egg shell thin, with or without filaments, and usually becomes destroyed: 
embryonal shell (embryophore) thick, radially striated. 
Bladder worm stage, a cysticerc-us, ccenurus, or echinococcus, in herbivorous or 
omnivorous animals; adults in carnivorous animals. 
Type gents. — Tsenia Linnieus, 1758. 
This subfamily contains two genera, represented among the parasites 
of man, namely, Tsenia and Echinococcus; the former is represented 
among the intestinal parasites of man, the latter (see p. 75) among the 
somatic parasites of man. 
Genus TAENIA « Linnaeus, 1758. 
Generic diagnosis. — Tseniinse (p. 23): In general, same as diagnosis of subfamily 
Tseniinse; larval stage a cysticercus. Adults in carnivorous mammals; larval stage 
chiefly in herbivorous and omnivorous mammals. 
Type species. — Tsenia solium Linnaeus, 1758. 
This genus is divided into several subgenera. which some authors 
have recognized, not entirely without reason, as entitled to full generic 
rank. These subgenera — or. if one prefers, genera — may be distin- 
guished as follows: 
KEY TO THE SUBGENERA (OR GENERA) OF TJENTA. 
(For forms reported for man follow roman type.) 
1. Segments always more than 10, usually more than 100; lateral uterine 
branches distinct; vitellogene gland triangular, with one side parallel 
to posterior margin of segment; larval stage never forms brood 
capsules 2 
Strobilla composed of head and three segments, only one of which is gravid 
at a time; lateral uterine branches often quite indistinct; vitellogene 
gland globular; larval stage an echinococcus, which forms brood cap- 
sules inside of which the scoiices develop Echinococcus (p. 75) 
2. Head with distinct rostellum armed with double crown of hooks 3 
Bostellum rudimentary; hooks small and become lost very early, so that 
head appears unarmed, the crown of hooks being replaced by a struc- 
ture known as the ‘‘apical” or “fifth” sucker; larva a cysticer- 
cus Tseniarhynchus (p. 26) 
3. Larva a cysticercus, namely, a small bladder worm with one scolex. Tsenia (p. 36) 
Larva a ccenurus, namely , a bladder worm with numerous heads, but without 
brood capsules Multiceps . * & 
a Synonyms. — See synonymy of subgenera Tsenia, p. 36, and Tseniarhynchus, p. 26. 
& Xot represented among the parasites of man. Multiceps Gceze, 1782; Polycepha- 
lus Zeder, 1800; Ccenurus Rupolphi, 1808; Polycephops Rafinesque, 1815; Csenurus 
Cuvier, 1825a; Canurus Goodsir, 1844g. 
