NEMATOIDEA. 645 
appears red from the blood with which the intestine is usually gorged. An analogous species, found on the Eel, 
was long mistaken for the young of that animal. 
Ophiostomus, have the body formed as in the preceding, but the mouth cleft across, which gives the appeax’ance 
of two lips. O. cystidicola, is found in the air-bladder of some Fishes. 
Ascaris (the Ascarides), — 
Have the body round, and slender toward each extremity. The mouth is furnished with three fleshy 
tubercles, among which there is a short tube, which the animal can protrude as occasion requires. 
The species are numerous, and inhabit the intestines of many animals. The females, which are far more 
numerous than the males, have the intestinal canal straight, and an ovary divided into two branches, which is 
several times longer than the body, and opens by a single oviduct at about one-fourth of the length from the 
anterior extremity. The males have also a single vessel, very long, and with the external organ, which is near 
the tail, sometimes double. Two white filaments, one extending along the back, and another along the belly, 
have been considered as nerves ; and two thicker ones, extending along the right and left sides, have been con- 
sidered as muscles, as a circulating system, and even as a breathing apparatus. Some species, as A.lumbricdides, 
have the head without lateral membranes. This species is found, without any remarkable difference, in Man, in 
the Ox, the Hog, and all the varieties of the Horse family ; it has sometimes occurred fifteen inches in length. It 
is naturally of a white colour ; and, from what has been said of its reproductive organs, its power of multiplication 
is excessive. It occasions disease, and even death, especially in children, or in all cases where it ascends from 
the intestines into the stomach. A. vermicularis, which has a small membrane on each side of the head, is very 
common in children, and also in adults, when afflicted with certain diseases. It chiefly inhabits the rectum, at 
the extremity of which it causes intolerable itching. Its length is not more than half an inch, and its body is 
thickest in the anterior part. It is an exceedingly active little animal, and derives its name from the Greek verb, 
“ to leap, or move.” 
Strongylus,— 
Have the body round, and the vent of the male inclosed in a sort of purse variously formed, which is 
regarded as the sheath of the organ of generation, which can be protruded from it. The female is 
Muthout this apparatus, and thus more nearly resembles the Ascarides. 
Some species have the mouth ciliated, or toothed, among which is S. equinus, which is about two inches long, 
with a hard spherical head, small soft spines round the mouth, and three lobes in the caudal appendage. It is 
very common in the intestines of the Horse ; and, so far as is known, in those of all the solipede family of pa- 
chydermatous animals. Sometimes it makes its way to the arteries, and there occasions aneurisms, and other 
unpleasant diseases. 
Other species have the mouth with tubercles, or papillae, and among these one of the most remarkable is 
S. gigas, the largest worm which is known to inhabit the intestines of any animal. It grows to the length of two 
or three feet, and is as thick as the little finger. It is usually found in the kidneys of various animals, as the 
Wolf, the Dog, the Marten, and even Man ; where it is coiled up, and inflates the organ, causing great pain. 
Sometimes small ones pass off" with the urinary discharge. It is not, however, confined to the kidneys, but is 
met with in other viscera. Its usual colour is a fine red ; the mouth has six papillae ; the intestine is straight, 
with cross furrows ; the ovary is simple, and three or four times the length of the body. It is understood to have 
a posterior opening, and also one near the mouth. M. Otto has considered a slender white thread, which passes 
along the abdomen, as being the nervous system. 
Spiropterus, have been separated from the Ascarides. They have the termination of the body spiral, with two 
wing-like membranes, between which is the reproductive organ. One species is occasionally found in the human 
bladder, and another in the stomach of the Mole,— to the villous coat of which it attaches itself by a small tubercle. 
Pkgsoloptera, has a small bladder between the wing-like membranes. Sclerottoma, has the mouth furnished 
with six small scaly plates. It is found in the Horse and the Hog, Liorhynchus, has the mouth in the form of a 
small proboscis, with which it penetrates the cavity of the viscera. 
Pentastoma, have the body flattened, and sharp in the sides, and the transverse rugse crenulated. The skin is 
thin and weak ; the head broad and flat, with the mouth beneath, and a longitudinal slit on each side, from which 
issue the hooks whereby the animal adheres. The intestine is straight, and the reproductive organs long and 
tortuous. A white filament surrounding the mouth, and two filaments which proceed from it, appear to be the 
nervous system. One species, P. tcenio'ides, occurs in the frontal sinuses of the Horse and Dog, and attains a 
length of about six inches. Prionoderma, resemble the former, only the mouth is terminal, and has two 
small hooks. 
Cuvier includes the following genera of intestinal worms in this order, but gives it as his opinion that, 
when they are better known, they will require subdivision as a distinct family. 
Lern,®a, — 
Have the body resembling the former both in its external and its internal organisation ; but it is pro- 
longed into a sort of neck of a horny consistency, at the end of which is the mouth, variously armed 
with plate-like appendages. It insinuates the mouth and these appendages into the gills of fishes. 
