128 MISS G. SWEET ON THE SPERMIDUCAL 
the main duct may either (a) leave the substance of the gland 
before the branches from the separate lobes have united, as in 
Megascolex Frenchi; or (b) it may leave the gland as a single 
duct, as in the great majority of cases, e. g., Megascolexr Dendyt, 
M. tasmanica, or Digaster armifera. 
Another variation connected with the spermiducal duct is in 
the presence of a muscular swelling or bulbus on each side in 
Megascolex Fielderi and Fletcherodrilus unicus. In the latter it 
partakes more of the nature of a swelling caused by an enormous 
and somewhat sudden thickening of the muscular layer of the 
duct-wall, straight through which the duct runs on its way to 
join its fellow of the opposite side, and open to the surface. In 
Megascolex Fielder, however, it is different. The bulbus is almost 
spherical (m.0., Pl. 14. fig. 14), and similar in size to that in 
F. unicus. The duct is sharply bent just before it enters the 
side of the bulbus, which it does obliquely. Within the bulbus 
the duct makes a complete coil, the vas deferens accompanying 
it until it opens into the duct a short distance from the external 
opening. 
(2) Vasa deferentia.—In accordance with the usual presence 
of two pairs of rosettes, there are generally two pairs of vasa 
deferentia. Even when the second pair of rosettes is absent, 
the two vasa deferentia are usually present on each side. Rarely 
there may be only one pair of vasa deferentia, e. g., Megascolides 
intermedius and DMegascolex Fieldert. They may join when there 
are two on each side as soon as possible after the 11th segment, 
z.€. in the 12th, e. g., Megascolex tasmanica, M. minor; or they 
may unite in the 13th or 14th segments, not always at the same 
level on the two sides, e.g., Fletcherodrilus unicus, Megascolex 
Frenchi, M. rubra. They may join just before they reach the 
spermiducal duct, as in Megascolides insularis, M. hobartensis, 
Cryptodrilus illawarre, Diplotrema fragilis, Diporocheta Bakert, 
Megascolex Illidget, Digaster gayndahensis, D. excavata; or they 
may join as they enter the duct, e. g., Megascolides attenuatus, 
MM. australis, M. tuberculatus, Dipcrocheta Copelandi, Megascolex 
Hoggit, M. Dendyt, I. intermedius, Digaster armifera, D. syl- 
vatica, D. minor, D. brunneus ; or they may open into the duct 
quite independently of each other, e. g., on opposite sides of the 
duct—such are Megascolides victorie, M. roseus, Cryptodrilus 
cooraniensis, Megascolex dorsalis, Digaster queenslandica. 
Variations in the relations of the spermiducal duct to the vasa 
