187 
Neorhynchus cylindratus n. sp. 
Large Neorhynchi, bodies almost straight. Females 10—15 mm. 
long, maximum breadth a short distance caudad of proboscis,:0,7 mm. 
Males 4,5—8,5 mm. long, maximum breadth located as in females, 
0,5—0,7 mm. Proboscis subglobular, slightly broader than long, length 
0,149 mm., width 0,172 mm. Hooks in three circles, six hooks to a 
circle, those in adjoining rows alternating. Terminal hooks 0,079— 
0,097 mm. long, sharply recurved, strong, 0,014 mm. thick at base, root 
0,058 mm. long, 0,029 mm. wide. Middle row 0,037 mm. long, 0,005 mm. 
thick at base. Basal row 0,021— 0,025 mm. long, 0,003 mm. thick at 
base. Embryos 0,049—0,051 mm. long, 0,015—0,021 mm. broad. In 
intestine of Meer a salmoides (Lacep.), Peter Lake, Minnesota. 
ZI \ _ DER 
RS 
Figure 4. N. cylindratus n. sp. Proboscis (X 145), hooks (X 465), embryos ( 465. 
Camera lucida drawing. 
There is but very little indication of the crescentic shape in the 
bodies of N. cylindratus. Moreover the maximum diameter of the body 
instead of occupying a region in the middle or anterior third of the 
body is located just a short distance behind the base of the proboscis. 
From this maximum diameter the body tapers gradually posteriad to 
about one third the maximum diameter at the posterior tip. The anterior 
end narrows rapidly to the point of union of the proboscis and body 
where the diameter is one fourth the maximum diameter. The hooks 
while of the general type of those found in N. emydis‘and N. tenellus, 
differ from each of these in rather important details of size and propor- 
tions. The basal row of hooks in N. emydis may almost equal the second 
row while in N. cylindratus and N. tenellus the basal hooks are consider- 
ably shorter than those of the middle row. The terminal hooks of N. 
cylindratus are shorter than those of N. tenellus. The subcuticula is 
0,075 mm. thick. The circular canals or lacunae contained within this 
tissue at times form an irregular network of small branches. The 
