128 
FRANK E. BEDDARD. 
character (in Allurus), and the terminal section is not in any 
way widened out to form a chamber which might be compared 
with an atrium. The term prostate, in the sense in which it 
has been used in the foregoing pages, is not applicable to the 
mass of glandular cells which surround the end of the vas 
deferens in Allurus; the structure in question is more rightly 
to be compared to such a group of glandular cells as that 
which surrounds the termination of the vas deferens in the 
Enchytraeidse (Yejdovsky 19 ). 
Summary. 
The most important facts described in the present paper 
are : 
(1) The independence of the vasa deferentia and atria in 
Acanthodrilus (PI. XIII, fig. 12) ; the two vasa deferentia 
of each side unite just before their opening on the eighteenth 
segment. The atria (= “prostates”) open separately upon the 
seventeenth and nineteenth segments. 
(2) The independence of the single vas deferens and its 
atrium in Typhaeus; they open near together on the same 
segment — the seventeenth (PL XII, fig. 1). 
(3) The occurrence of six pairs of setae in each (setigerous) 
somite of Deinodrilus (PI. XIII, fig. 9 ). 
(4) The completely double dorsal blood-vessel of Acantho- 
drilus annectens and of Deinodrilus Benhami. 
(5) The enclosure of each half of the dorsal vessel of Dei- 
nodrilus in a separate ccelomic space (PI. XIII, figs. 6, 7). 
(6) The presence in Moniligaster Barwelli of an atrium 
consisting of a thick glandular covering of peritoneum of a 
layer of muscular fibres, and finally, of a single layer of 
columnar epithelium (PL XII, fig. 11). The atrium is similar 
in structure to that of Rhynchelmis. 
