PARENCHYMATA. 647 



E. gigas, is the largest known species ; it is found in tne Hog and the Wild Boar, and the females are sometimes 

 fifteen inches long. E. haruca 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. 



Eestucaria, with only one sucker upon or under the anterior part. They are found in various birds, reptiles, 

 and fishes. 



Amphistoma, with a sucker at each end, in various vertebrated animals. 



Caryophyllaus, 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. 



Dutoma, 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 hepaUca [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 MoUusca, all the individuals appear 

 to be bisexual, and have a mutual coitus. [The eyes are pmced 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. Tlie 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. 

 Tliough they accompany the rot in sheep, they do not appear to cause it, neither does their multiplication appear 

 in all cases 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. beloni, has been found parasitical upon the common Sea-pike, Belone 

 vulgaris. 



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. 



Uectocotylus, 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 four or 

 five inches long, and they are chiefly parasitical upon the Cuttle-fishes. 



