A Morphological Study of Strongylus douglasi, Cohhold. 263 
female the distance between the rings corresponds to 3 ^ at a third of the 
distance between the anterior extremity and the neural commissure, 2'6 /i 
at the height of the nerve commissure and about 2*2 ^ in the latter third 
of the body. In the male the striation continues on all the surface of the 
bursa, where however the lines are not so clearly visible. In the female 
they do not reach altogether the caudal extremity, but stop at about 
10 from the end. 
The longitudinal muscles of the body (Figs. 4, 6, 7 m.) begin immedi- 
ately after the oral hollow and are all along roughly equal in thickness to 
the cuticle of the male ; in this sex they terminate at the basis of the 
bursa, whilst in the female they are somewhat thinner than the cuticle in 
the posterior third of the body and extend to the end of the tail. 
Alimentary Tract. — The mouth is terminal and nearly semi-spherical. 
Cobbold says it is unarmed, but I am able to distinguish six triangular 
teeth or cutting plates, which are quite distinct in transversal sections 
and which occupy a considerable part of the lumen (Fig. 1). The 
oesophagus is dilated by a bulb at about a tenth of the total length of the 
body (Figs. 1, 2, 3 es.b.). In both sexes the intestine is straight, but in 
the male the terminal portion is united to the deferential duct so as to 
end in the cloaca after having been applied to the ventral portion of the 
body ; in the female it diminishes in size before ending in the anal 
aperture a little before the caudal extremity. 
In the female the rectal muscles (Fig. 9 r.m.) are fan-shaped and 
placed between the dorsal wall of the terminal intestine and the dorsal 
wall of the body and occupy a space measuring about 70 yu. The intestinal 
muscles are long, thin, and finely ramified. The inferior ramifications are 
seen in Fig. 9 i.m. 
c/.p. 
Fig. 5. — Outline of the head with 
cephalic papillae. Magnifica- 
tion : 1150 diameters. 
