352 ENTOZOA. 
Tricnostoma, Rud.—Caritiaria, Zeder, 
Where the anterior portion of the body is but gradually attenua- 
ted(1). 
Oxyuris, Rud. 
Where the posterior part of the body is attenuated in the manner 
of a thread. 
O. curvula, Rud.; Goetz., VI, 83 Encyc., XXXIII, 5. From 
one to three inches in length. It inhabits the cecum of the 
Horse(2). 
CucULLANUS. 
Where the body is round, and most slender posteriorly. The head 
is obtuse and invested with a sort of hood that is frequently striated; 
the mouth is round. 
They have hitherto been found in Fish only. The most com- 
mon species is that which inhabits the Perch—C. lacustris, Gm.; 
Geetz., IX, A, 3; Encyc. XX XI, 6—and also infests the Pike, 
&c. It is viviparous, about an inch long, as thick as a thread, 
and of a red colour, owing to the blood with which its intes- 
tine is usually filled(3). 
OPHIOSTOMA. 
The same kind of body as the preceding, but distinguished by a 
transversely cleft mouth, and consequently furnished with two lips. 
O. cystidicola, Rud.; Cystidicola, Fischer, Monog. It is found 
in the natatory bladder of certain Fishes(4). 
(1) See Rud., Syn., 13. 
(2) Add Ox. alata and Ox. ambigua, Rud., Syn., 19. 
(3) For the other species, see Rud., Hist., I, 102, and Syn., 19. 
(4) Rud., Hist., If, 117, and Synop., 60. 
