362 ENTOZOA.: 
form of a proboscis armed with little hooks bent posteriorly, and sus- 
ceptible of being retracted or protruded by the action of particular 
muscles. Atits extremity we sometimes observe a papilla or pore 
which may be an organ of absorption, but it is certain that if the 
animal be plunged into water it becomes universally distended, and 
absorbs that liquid through the whole surface, on which it is thought 
we can discover a network of absorbent vessels. No other parts 
that can be compared to intestines are visible internally, than two 
slightly elongated ceca attached to the base of the tubiform promi- 
nence; a vessel extends throughout its length on each side. A 
thread that runs along the inferior face of the animal is considered 
by M. de Blainville as its nervous system; but neither Rudolphi 
nor Cloquet coincide with him. Certain species have a distinct ovi- 
duct; in others the ova are disseminated throughout the cellulosity 
or parenchyma of the body. The males are provided with a little 
bladder at the end of the tail, and very distinct internal vesiculz 
seminales. We may believe that they fecundate the ova after they 
are extruded. 
These worms cling to the intestines by means of their proboscis, 
and frequently penetrate through them, so that individuals are some- 
times found in the thickness of their tunics, and even in the abdo- 
men, adhering to their external parietes. 
E. gigas, Gm.; Geetz., X, 1—6; Encyc. XX XVII, 2—7. The 
largest species known; it inhabits the intestines of the Hog 
and Wild Boar, where the females attain a length of fifteen 
inches(1). 
Certain species, in addition to the prickles on their proboscis, are 
armed with them in some other part of the body. 
Hzruca, Gm. 
Only differing from Echinorhynchus in the prominence, which is 
reduced to a single crown of spines, terminated by double hooks. 
H. muris, Gm.; Echinorhynchus heruca, Rud.; Geetz., IX, 
B., 123° Bacyc., Vers, XXXVII, 1(2). It inhabtie the liver of 
Rats. 
; 
(1) For the other species, see Rud., Hist. IJ, 251, and Syn., P- 63. 
(2) Id., Ib., 292, etiseq. 
