430 FRANK E. BEDDARD. 
and from certain glands of other Earthworms (e.g. Urocheta), 
which have been regarded as the homologues of the calciferous 
glands. 
Vascular System.—The dorsal vessel is like that of A. 
multiporus; it is completely double from end to end of the 
body ; for the most part the two vessels are placed close side 
by side, but they do not fuse at the points where they traverse 
the mesenteries ; on the gizzard the two dorsal vessels come to 
be somewhat widely separated. The transverse vessels uniting 
the dorsal with the ventral vessel form large conspicuously 
dilated ‘‘ hearts” in segments x—x1 (inclusive). In all 
these points Acanthodrilus antarcticus agrees closely 
with both A. multiporus and A. annectens. 
Sevta.—The characters of the intersegmental septa appear to 
offer useful specific characters in this genus; in some species 
a certain number of the anterior septa are greatly thickened ; 
the number of septa which are thus enlarged, and the degree in 
which their thickness is increased, differs, for instance, in the 
present species and in A. multiporus. In A. antarcticus 
the septa separating segments VII—VIII, VIII—IX, IX—x, x— 
XI, XI—xII, are specially thickened, particularly the last four. 
In A. multiporus the same septa, with the addition of one 
in front and one behind, are thickened, but not so much as in 
A.antarcticus. 
Genital Organs.—The testes are two pairs of minute 
bodies in segments x and x1; each is attached to the anterior 
septum of its segment close to the junction of the septum with 
the body wall; it is placed exactly opposite to the funnel of the 
vas deferens. 
The ovaries occupy a corresponding position in segment 
xuir; the funnel of the oviduct having a relation to them similar 
to that of the funnel of the vas deferens to the testis. The 
two pairs of atria are situated in the seventeenth and nine- 
teenth segments respectively ; each is a much-coiled glandular 
tube communicating with the exterior by means of a narrower 
tube with thick muscular walls. The structure of these organs 
present, in fact, no differences from other species, 
