ASCARIS. 153 
the hind-end of the male is slightly coiled, and has a pair of 
Bxterna) ™inute bristles ur aza/ sete protruding from the 
Features, 202! aperture. The body is of a whitish 
“colour, and it has four lines (a dorsal and 
ventral and two lateral) along its surface. 
Fig. 87.—DIAGRAMMATIC TRANSVERSE SECTION OF ASCARIS 
MEGALOCEPHALA. (fd nal.) 
Dorsal Nerve Cord. 
Cuticle., 
Ectoderm,, 
Muscle Cell. 
Ts 
Excretory 
Duct, 
Oviduct. 
Uterus. Ventral Nerve Cord.. 
The mouth is at the anterior end, surrounded by a dorsal 
and two lateral lips which bear sense-papille, probably 
tactile. The anus is a little distance from the posterior end 
on the ventral surface. Some little way behind the mouth 
is a minute median ventral pore, the excretory opening. 
On dissection we find a definite body-cavity* in which 
lie freely the alimentary and reproductive organs: The 
mouth leads into a pharynx with muscular walls lined by 
chitin. The suctorial pharynx opens into a long dufestine 
terminating in the azus. The intestinal epithelium is said 
to secrete on both surfaces a delicate cuticle. 
* This cavity may be a modified coelom or may be an archiccele : the structure 
of the excretory organs points to the latter. 
