I 
PARENCHYMATA. 
647 
E. gigas, is the largest known species ; it is found in the Hog and the Wild Boar, and the females are sometimes 
fifteen inches long. E. Jueruca is a smaller species, with only one row of spines on the proboscis. It has been 
fonnd in the liver of the Cat. 
THE SECOND FAMILY OF THE PARENCHYMATA,— 
The Tremadotea, — 
Have the under part furnished with cup-like discs, or suckers, by which they adhere. Those which are 
parasitical in other animals, may all be included in one genus, 
Fasciola, — 
But it admits of subdivision, according to the form and arrangement of the suckers. 
Festucaria, with only one sucker upon or under the anterior part. They ai’e found in various birds, reptiles, 
and fishes. 
AmpMstoma, with a sucker at each end, in various vertebrated animals. 
Caryophyllceiis, have the head broad, winged at the margin, with a two-based sucker underneath, and sometimes 
another on the opposite end of the body. One species is known, and it infests fresh-water fishes, especially the 
Bream. 
Distoma, has a sucker at the anterior extremity, and another on the under part, a little farther back. The species 
of this genus, or rather subgenus, are very numerous, and inhabit many animals ; some of them even the wrinkled 
membrane surrounding the eyes of birds ; but there appear to be others in salt water or fresh, which are not para- 
sitical upon any animal. 
Distoma hepatica [the Fluke, so called from its shape, is but too well known as infesting the liver of the Sheep, 
and if not occasioning “ the rot,” at least greatly aggravating its symptoms, and accelerating its progress.] It is 
also found in other ruminants, in the Horse, the Hog, and even in Man. It is from three quarters of an inch to 
an inch and a quarter in length, and its form is that of an oval leaf, pointed at the posterior extremity, and with 
a narrow portion at the anterior. The first sucker is at the base of this narrow portion, and leads to two branched 
tubes. Behind the sucker, there is an erectile tentaculum, which appears to be the male organ ; and behind this 
is the second sucker. The mineral vessels are convoluted through the middle portions ; and the ovaries are also 
diffused through the body, and open near the male organs. As in many of the Mollusca, all the individuals appear 
to be bisexual, and have a mutual coitus. [The eyes are placed on the most conspicuous part of the head, and 
like the eyes of birds, they are provided with horny rings, by means of which they command a great range of 
focal lengths. Some naturalists have considered the ramified tubes which proceed from the sucker as circulating 
vessels ; but this seems a mistake, as the convoluted vessels which the same naturalists have looked upon as in- 
testines, are the seminal vesicles and ovaries. The power of multiplication in these animals is immense ; and 
the ducts of a single liver have been found to contain more than a thousand, while the germs are quite innumerable. 
Though they accompany the rot in sheep, they do not appear to cause it, neither does their multiplication appear 
in aircases to render it more mortal, for sheep have died of rot with not more than a dozen of Flukes in the liver, 
while others have been alive with hundreds. Those sheep which are in the best condition, always have Flukes in 
them in the autumn ; but they are also the ones most subject to the rot. It is probable that these Flukes, or at 
all events the germs of them, exist in the water, or on the plants of humid and marshy places ; at all events, even 
the healthy sheep drop a few of them in the winter months ; and the deceased ones vast numbers ; and thus the 
rotten sheep taint both the flock and the pasture.] Echinotoma, have hooks on a projecting tubercle. 
Holostoma, — 
Have one half of the under surface of the body concave, and acting as a sucker. They are found in 
some Mammalia and birds. 
Hexastoma, have the body flattened underneath, with six suckers on the under part. They are found in fishes, 
in reptiles, and even in the human body, in very peculiar situations. 
Cyclocotula, — 
Have eight cups ranged in a circle on the lower part of the body backwards, and a small proboscis in 
front. One small species, C. heloni, has been found parasitical upon the common Sea-pike, Belone 
Tristoma, is another subgenus, which resembles the Flukes. The body is broad and flat, with a pedunculated 
sucker on the under part, and two small ones anteriorly a little in advance of the mouth. There is a circular 
ramified vessel, the function of which is not well known, embedded in the parenchyma of the body. T. coccinea, 
about an inch broad, and of a bright red colour; attaches itself to the gills of the Sword Fish, and other large 
species. 
Hectocotylus, is one of the most singular genera in this family. The individuals are long worms, thick, but 
compressed in the fore part, and having the whole of the under surface covered with suckers, arranged in pairs ; 
and there is a sac at the posterior extremity, containing the folds of the oviduct. Some of the species are tour or 
five inches long, and they are chiefly parasitical upon the Cuttle-fishes. 
