CONTRIBUTIONS TO COMPARATIVE PATHOLOGY. 621 
fiftieth of an inch in diameter. Only a pair of the larger 
entozoa were found in each of the three largest tumours. The 
smaller species existed in countless numbers. 
“The tumours were composed of condensed accumulated layers 
of the sub-mucous cellular tissue, presenting a flat surface next 
to the muscular coat to which the larger tumours firmly adhered, 
and projecting with a rounded convexity towards the cavity of 
the stomach, where the sinuses opened and terminated. They 
did not contain any of the caseous secretion characteristic of 
struma , but were most probably caused by the irritation of the 
entozoa.” 
Mr. Owen gives the following account of these entozoa: — ■ 
“The male is about one-fourth smaller than the female. In 
both sexes the body is slightly attenuated at the two extremities. 
The caudal extremity is more inflected and obtuse in the male. 
The oral extremity in both is obtuse and truncate. 
“ The surface of the body appears to the naked eye to be 
minutely striated transversely. It is variegated by the white 
genital, and amber-coloured digestive tubes appearing through 
the transparent integument. When examined with a powerful 
lens, the anterior two-thirds of the body is seen to be covered by 
a series of minute reflected spines, presenting three distinct 
points — one large one in the middle, and two small lateral ones. 
“ The mouth is surrounded by a tumid circular lip, armed 
with six or seven circular rows of well-developed spinous pro- 
cesses of a similar complex structure to those on the body. The 
oral orifice itself presents the form of a vertical elliptical fissure, 
bounded on each side by a jaw-like membranous fold or process, 
the anterior margin of which is produced in the form of three 
straight horny points or processes directed forwards. These 
lateral processes can be protruded beyond the circular lip, by 
compressing the smooth spineless skin behind the latter; and 
the elasticity of the structure causes them to be again retracted 
on remitting the pressure.” 
Mr. Owen considers this nematoid worm to resemble most 
nearly some species referred by Rudolphi to the genus Strongy - 
lus, as the Strongylus trigonocephalus ; but the armature of the 
mouth is so remarkable in the present worm, that Mr. Owen is 
induced to regard it as the type of a new genus, which he pro- 
poses to denominate gnathostoma , from yvafio?, maxilla, and 
( TT0(xct , os, and he would thus describe it: — 
“ Gen. Char. Corpus teres, elasticum, utrinque attenu- 
atum. Caput unilabiatum, labio circulari tumido integro ; os 
emissile, processibus corneis, maxilliformibus duobus lateralibus 
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