145 
the inner of longitudinal fibres (fig. 2,7). The inner structure is a paren- 
chyma in which are embedded radiating, longitudinal fibres (fig. 2,8) and 
numerous deeply-staining gland-cells which are similar in size and appe- 
arance to the subcuticular cells. The ventral surface of the spheroidal 
body, which faces the genital sinus, has nomuscular coating and is divided 
by a deep transverse fissure into an anterior and a posterior half. Pro- 
jecting from this surface into the genital sinus are large curved spines 
(fig. 2, 5), the average length of which is 0,01mm. There are thus two 
groups of these spines, an anterior and a posterior group, the spines in 
the former group being directed anteriorly and those in the latter group 
posteriorly. 
LE 
Se 
SE ci 
Sg 02 ul 
Fig. 2. Genital sinus: longitudinal section. 1) Spheroidal body; 2) Tongue-like body; 
3) Genital pore (with the tongue-like body pushed partly through it); 4) Anterior 
pocket; 5) Spines on spheroidal body; 6) Circular muscles of spheroidal. body; 
7) Longitudinal muscles of same; 8) Radial muscles of same; 9) Common genital 
duct; 10) Metraterm; 11) Uterus; 12) Vas deferens; 13) Vesicula seminalis; 14) Ge- 
nital papilla; 15) Valve-like fold; 16) Ventral body-wall. 
The spiny surface of the spheroidal body forms thus the inner or 
dorsal wall of the genital sinus. The outer or ventral wall is formed 
partly by a muscular body which Jägerskiöld calls the tongue-like 
body. This structure (fig. 2, 2) is a sac the walls of which are very thick 
and made up of muscle fibres which run rather irregularly in several 
different directions. Like the spheroidal body its shape varies consider- 
ably in different individuals according to the condition of contraction 
10 
