NEMATOIDEA. 407 
longer than the body, which communicates with a (sometimes double) 
penis that protrudes through the anus. The latter opens under the 
extremity of the tail. 
Two white threads, one of which extends along the back, and the 
other along the belly, are considered by Messrs Otto and Cloquet as 
the nervous system of these animals; two other and thicker threads, 
one on the right and the other on the left, are considered by some as 
muscular, and by others as vascular, or even as trachee. 
In some, the head is destitute of lateral membranes. The most 
common species. 
A. lumbricotdes, L., is found without any essential difference 
in Man, the Horse, Ass, Zebra, Hemiona, Ox and Hog. It has 
been seen more than fifteen inches in length. Its natural colour 
is white, and it sometimes multiplies excessively, occasioning 
disease and death, particularly in children, or when it ascends 
into the stomach. 
Other species are furnished with a little membrane on each side 
of the head. Such is 
A. vermicularis, L.; Goetz., V, 1—6; Encyc. Méthod., Vers, 
XXX, pl. x, 1. Very common in children, and in adults af- 
flicted with certain diseases, in which it causes an insupportable 
itching at the anus. It is not more than five lines in length, and 
is thickest anteriorly *. 
Stroneyius, Mul.t, 
Where the body is round, and the anus of the male is enveloped by 
a sort of bursa, variously shaped, from which issues a little thread 
that appears to be an organ of generation. These two last characters 
are wanting in the female, which has sometimes caused her to be 
taken for an Ascaris. 
In some of these Strongyli the mouth is ciliate or dentated. Such is 
S. equinus, Gm.; Str. armatus, Rud.; Miill., Zool. Dan., IT, 
xlii; Encye. Méthod., XXXVI, 7—15. Two inches in length ; 
head hard and spherical, and the mouth surrounded by small, 
soft spines ; bursa of the male trifoliate. Of all the Worms that 
infest the Horse, this is the most common ; it even penetrates into 
the arteries, where it occasions aneurisms. It is also found in the 
Ass and Mule. 
The mouth of others is merely surrounded by tubercles or papilla. 
Such particularly is the 
S. gigas, Rud.; Ascaris viceralis and Asc. renalis,Gm. ; Redi., 
An. Viv. in An. Viv., pl. VIII and IX; Le Diocropuyme, Collet- 
Meygret, Journ. de Phys., LV, p. 458. The most voluminous of 
all known intestinal Worms ; it is upwards of two or three feet 
in length, and as thick as the little finger. The most singular cir- 
cumstance attending this Strongylus is that it is most usually de- 
veloped in one of the kidneys of various animals, such as the 
* For the remaining species of Ascarides that infest animals, see Rud., Hist., II, 
128, et seq. and Synop., p. 37, et seq. 
T Srpoyyvaos, round. 
