192 
LECTURE XII. 
Of the whole tribe of Vermes none is more cu- 
rious than the genus called Tcenia^ which is ex- 
tremely numerous, and presents a great diversity 
of appearance in the different species j some be- 
ing of a globular form, with a small neck and 
head, while others are of immoderate length, with 
the body divided into very numerous joints ; in 
some species very close set ; in others more dis- 
tant. The head in all the Tseniae, or Tape-Worms, 
as they are commonly called, is of a highly curious 
structure ; being of a rounded and slightly flat- 
tened shape, with a small orifice in the middle, 
and four much larger ones placed round the mar- 
sin, while the whole circumference of the head is 
beset with a double, and, in some species, with a 
single row of sharp, reversed, crooked spines, by 
the assistance of which the animal is enabled to 
adhere tenaciously to the part in which it resides. 
It is surprising that Linnaeus should have main- 
tained that these animals had no distinct or pro- 
per head, and that Tyson and others, who had 
described them with one, were mistaken, A clear 
general idea of the genus Taenia may be obtained 
bv inspecting a few plates of some of the principal 
species. 
