458 CLASS ECHINODERMATA. 
INTESTINA CAVITARIA. (ENTOZOA NEMATOIDEA, Rud.,) 
Which have an intestinal canal floating in a distinct abdo- 
minal cavity, and a mouth and anus. 
INTESTINA PARENCHYMATA, 
Whose body encloses, in its parenchyma, some viscera, but 
imperfectly terminated, and most frequently resembling vas- 
cular ramifications, even sometimes being not at all per- 
ceptible. 
THE FIRST ORDER OF INTESTINA. 
CAVITARIA. NEMATOIDEA, Rudolphi, 
COMPREHEND those whose external skin, more or less fur- 
nished with muscular fibres, and in general striated trans- 
versely, contains an abdominal cavity, in which floats a dis- 
tinct intestinal canal, proceeding from the mouth to the anus, 
and where also are,generally observed some distinct organs for 
the two sexes. The intestine is united to the neighbouring 
parts, and to the general envelope by numerous filaments, in 
which some have imagined that they discovered nutritive 
vessels, others trachez, but without any proof. It is impos- 
sible to observe in these animals any true circulation, but 
there appears to be in many, one or two nervous cords, pro- 
ceeding from a ring which surrounds the mouth, and running 
the entire length of the body, on the internal face of the 
envelope. 
The intestine is generally straight, and tolerably broad ; 
the cesophagus is frequently more slender, and in some species 
we remark a stomach more ample and more robust. The 
