208 FRANK E. BEDDARD. 
origin. The sperm-sacs have a slightly racemose appearance ; 
they are attached to the septum by a stalk; this stalk is hol- 
low, and seems to open into the cavity of the 11th segment ; it 
is of course lined by peritoneum, which is especially thick on 
that part of septum near to the origin of the sacs. The walls 
of the sacs are muscular and thin; there are also trabecule of 
muscular fibres which divide the interior of the sacs into com- 
partments ; these spaces are full of developing sperm. Michael- 
sen has described in Eudriloides gypsatus, in addition to 
these sacs, a sac in the 11th segment. I have looked carefully 
for this, but can only find a mass of sperm in that segment. 
This mass of sperm is not enclosed by any walls, and there are no 
blood-vessels for the supply of any sac, such as are abundantly 
obvious in the case of the sperm-sacs of the 12th segment. 
The sperm duct runs along the body-wall just at the line 
of implantation of the ventral sets; it is accompanied in its 
course by a blood-vessel. Near to the external orifice of the 
atria the sperm-duct perforates the outer coat of the atrium of 
its own side, and comes to lie where it is represented in fig. 1. 
Anteriorly the sperm-duct of each side opens into the cavity of 
the 11th segment by a large and much folded funnel; the two 
funnels together occupy a great deal of the space in the 11th 
segment; above the nerve cord the two funnels become fused 
together. The atria extend through three or four segments ; 
they lie side by side, and are never coiled; this coiling, which 
is often seen in the long atria of other species, is rendered 
impossible in the present case by the thick muscular coat 
which forms the outer layer of the atria. This muscular layer 
consists of longitudinal and circular fibres; the circular fibres 
are internal. The epithelium lining the atrium appears to 
consist of two layers, but these are not by any means so thick 
as in other Eudrilide ; in transverse sections of the atrium the 
lumen is seen to be crescentic; the convexity of the crescent 
is dorsal; below this lies the sperm-duct, which, as already 
stated, lies within the atrium: the sperm-duct passes just be- 
tween the epithelium and the muscular layers; it is accom- 
panied by a blood-vessel. Towards the external pore of the 
