108 
EfiANK E. BEDDARD. 
several pores in each segment. The nephridial system of this 
worm is in fact like that of Acanthodrilus multiporus. I 
have not as yet worked it out in detail; this I hope to do later. 
Coelom. — It is the rule among the higher Oligochseta that 
the coelom is a spacious cavity divided into a series of cham- 
bers by the transverse septa ; only in the first few segments of 
the body is this arrangement interfered with by the develop- 
ment of strands of muscular fibres uniting the pharynx with 
the parietes. In these segments the coelom forms an irregular 
system of lacunae. Furthermore, the saccular outgrowths of 
the septa in the genital segments which envelope the testicular 
products, and sometimes also include the testes, the vasa 
deferentia funnels, and part of the ventral blood-vessel and 
nerve-cord, may be looked upon as specialised parts of the 
coelom. Lastly, in Eudrilus there is a “perigonadial” space 
surrounding the ovary. 
In Deinodrilus the dorsal blood-vessel is surrounded by a 
special coelomic space in a way that is, at present, unique 
among Earthworms. This space does not appear to exist in 
the first fifteen segments ; after this point the two dorsal blood- 
vessels are not as plainly visible on a dissection of the worm as 
they are anteriorly ; the red colour of the blood is masked by 
the whitish colour of the tissues which form the walls of the 
perihsemal space. The fact that the blood-vessels are so clearly 
seen on dissection in the anterior segments, leads me to infer 
that here there is no perihsemal coelomic space ; but I am 
unable to support this view by a description of the micro- 
scopical appearance of the dorsal vessels in this region of the 
body, which I have not investigated by sections. 
PI. XIII, fig. 7, is a longitudinal section through one of the 
two dorsal vessels ; and PI. XIII, fig. 6, is a transverse section 
of the dorsal vessels more highly magnified. 
It will be seen from these figures that the blood-vessels are 
surrounded by a widish tube which is further divided into two, 
one for each of the paired vessels. 
The walls of this perihaemal space consist of a thin layer of 
fibres which are covered on both sides by peritoneal epithe- 
