STUDIES ON EARTHWORMS. 259 
worm, Urobenus, x. g., in which the single pair of seminal 
reservoirs extends through thirty or more somites. | 
In Urocheta, too, there is but a single elongated pair, 
occupying somites XIII, XIV, xv, as is also the casein Typheus. 
In Rhinodrilus there is but one pair, spherical in shape. 
But the most usual number seems to be two pairs, and though 
Perrier describes three pairs in Eudrilus decipiens (for in- 
stance), I fancy that the third pair are really only prolongations 
of the other reservoirs such as we have in Lumbricus. 
Two pairs occur in somites 1x and x in Anteus and 
Eudrilus; in somites x, x1 in Lumbricus;! in somites 
xI, x11 in Pontodrilus, Perionyx, in Pericheta and 
Acanthodrilus ungulatus. In all these forms the reser- 
voirs are very like those of Lumbricus, but in Moniligaster 
there are two pairs of seminal reservoirs, of which those in 
somite yiir are very small and globular, whilst those in somite 
x are much larger; the whole generative system in this worm 
is very complicated and curious. In Digaster are two pairs 
of grape-like organs in somites x, x1, which Perrier considers 
as “ testicules,” but whether they are testes or seminal reser- 
voirs is not apparent. 
In Plutellus in somite xm, and in Acanthodrilus 
obtusus in somite x11, there is a pair of grape-like organs, 
which contain bundles of developing spermatozoa. In Pleuro- 
cheta there are several enigmatical structures in the genital 
region, but whether the grape-like organs in somite x1I are 
the same thing as the smooth-looking seminal reservoirs of 
better-known worms seems to me uncertain, as Beddard says 
nothing of their structure. 
1 In Lumbricus the rudiments of the seminal reservoirs appear on each 
side as an anterior growth of the septum between the somites rx and x, as 
a similar pair of anterior outgrowths on the septum between x and x1, anda 
further similar pair of posterior outgrowths on the septum between x1 and 
x11. There are thus three pairs of saccular rudiments, on each side: of which 
the two anterior pairs unite to form a single organ in somite x, whilst 
a similar union takes place between those of the right and left sides in 
somite XI. 
