408 ENTOZOA, 
Wolf, Dog, Mink, and even Man, where it lies doubled up, dis- 
tending that organ, destroying its parenchyma, and probably oc- 
casioning the most excruciating agony to the animal in which it 
resides. It has been occasionally known to pass off with the 
urine, while yet small. It sometimes inhabits other viscera. Its 
usual colour isa beautiful red; the mouth is surrounded with six 
papilla; the intestine is straight and transversely rugose, the 
ovary simple, three or four times the length of the body, com- 
municating exteriorly by a hole a little distance posterior to the 
mouth, and, as it appears, by the other extremity, with the anus. 
An extremely attenuated white thread that extends along the 
abdomen is considered by M. Otto as the nervous system *. 
Naturalists have lately separated from the Ascarides and Strongyli 
the 
SPIROPOPTERA, 
Where the body terminates spirally, and is surrounded by two wings, 
from between which issues the penis +. 
One species is said to be occasionally found in the human 
bladder. Another, the 
Sp. strumesa, Nitsch, inhabits the Mole. It penetrates into a 
ring which it forms in the villous coat of the stomach, and at- 
taches itself there by a small tubercle f. 
PHYSALOPTERA, 
Where the posterior extremity is provided with a bladder between two 
little wings, and a tubercle from which the penis originates §. 
ScLErostoma, Blainv., 
Where the mouth is furnished with six small dentated scales. 
They are found in the Horse and in the Hog. 
Lioruyncuus, Rud., 
Where the mouth is in the form of a little proboscis ||. 
PrentTAstoma, Rud., 
Where the body is depressed and trenchant on the sides, and the trans- 
versal rug are marked by numerous crenulations, The skin is thin 
and slight; the head broad and flattened ; and the mouth beneath; on 
each side of the latter are two small longitudinal clefts, from which 
issue little hooks. The intestine is straight and the genital vessels 
are long and tortuous. Both the formerand latter open externally at 
the posterior extremity. Near the mouth are two ceca, as in Echi- 
norhynchus. A white thread encircles the mouth and gives off two 
descending trunks, in which I think I have recognized the appear- 
ance of a nervous system, 
* Otto, Magas., of the Soc. Nat. Berl., 1816, p. 225, pl. v. 
+ Rud., Syn., p. 22. 
+ Nitsch, Monog., Gm., Hal. Sax., 1829 
§ Rud., Syn., 29. 
| Bud., Hist. II, 247, et seq. 
