ACALEPHA. 
555 
This tribe is known by the name of Hydatids, and inhabit 
the liver and other parts of the animal system. 
Genus ECHINOCOCCUS. —Rudolphi. 
Generic Character .— Vesicle externally simple or duplex, 
consisting of a cyst, with several individuals inclosed. 
Echinococcus hominis. —The Human Echinococcus. 
Plate Cl I. fig. 10 . 
Body somewhat round, destitute of organs of vision, and ap¬ 
pearing a globular vesicular mass. Inhabits the internal tex¬ 
tures of the human body. 
CLASS XIII.—ACALEPHA. 
With a gelatinous body, circular and radiated, with a soft 
transparent skin; susceptible of considerable contraction and 
dilation. 
The animals of the class Acalepha are either fixed by their 
base to some extraneous substance, or float independently in the 
sea. Their bodies appear to be destitute of muscular fibre, are 
entirely of a gelatinous consistence, and are susceptible of dilar 
lion and contraction. 
Section I. 
Body fixed to other substances.—It contains three genera: 
I. Actinia; 2. Zoanthus; 3. Lucernaria. 
Genus ACTINIA.— Lamarck. 
Generic Character .—With a cylindrical, fleshy, very con¬ 
tractile, and simple body; attached by its base, but having the 
power of removing itself; mouth terminal, margined with from 
one to numerous rows of radiated tentacula, disappearing when 
the animal contracts its orifice; i*esembling a flower in blossom 
when dilated. 
2 z 2 
