Cestode &e. from Spitsbergen. 423 
in depth nearly a quarter of the total dorso-ventral diameter 
of the worm. ‘The longitudinal musculature 1s well- 
developed, consisting of an inner layer (fig. 2, i./.m.) of 
larger, and an outer layer (fig. 2, 0./.m.) of smaller, bundles 
of fibres. Of the former there are about twenty bundles 
dorsally and a similar number ventrally. They he imme- 
diately outside the very scanty layer of transverse fibres 
(fig. 2, ¢.m.), which forms the boundary between the cor- 
tical and medullary parenchyme. At the level of this 
transverse layer, on the ventral side, lie the two large 
ventral longitudinal excretory canals (figs. 2, 3, e.). Dorsal 
Anophryocephalus anophrys. Transverse section through 
a mature segment. 
c.8., Clrrus-sac 3 @., €., excretory vessels; g.a., genital atrium; 7.Zm., 
inner layer of longitudinal muscles ; x., 2., longitudinal nerves ; 
o.l.m., outer layer of longitudinal muscles; ov., ovary; t¢., 2., 
testes; ¢.m., transverse muscles; wt., uterus; vay., vagina; 
vit., yolk-gland, 
longitudinal canals and transverse connecting vessels between 
the ventral canals appear to be entirely absent. 
The genital pores are all on the right side. The genital 
ducts pass dorsally to the exeretory canal and ventrally to 
the longitudinal nerve of that side. The external pore leads 
by a narrow canal into a rather small genital atrium 
(fig. 2, g.a.), corresponding to that of Tetrabothrius, into 
which the cirrus-sae and vagina open separately, the latter 
ventrally to the former. Immediately below the opening of 
the vagina the wall of the atrium forms a small, rounded, 
