258 WILLIAM BLAXLAND BENHAM. 
as he points out, is additional evidence in favour of Lankester’s 
theory of there having been originally two pairs of nephridia to 
each somite. 
The nephridia in Lumbricus and others that have been studied 
are very well supplied with blood-vessels, which from time to 
time have dilatations on them, in which are frequently numerous 
blood-corpuscles ; these have been figured by Lankester (48) 
and Claparéde (11). These dilatations, however, are not con- 
fined to the nephridia, they occur on the vessels of the septa 
[and are particularly abundant on the grape-like pharyngeal 
glands of a new genus Trigaster]. 
Genital System.—Throughout this description, as also in 
future papers, I use the word “seminal reservoir” for the 
organs that Perrier and others call ‘“ testes ”’ or “ testicules.” 
The male generative organs consist of one or more pairs of 
seminal reservoirs, the sperm ducts and their “ciliated rosettes” 
(or funnels). The true testes are probably always hidden in a 
mature worm within the substance of the seminal reservoirs, 
though this is only known to be the case in Lumbricus [an 
Microcheta]. Besides these more important organs various 
accessory copulatory appendages are known. 
The Testes.—In Lumbricus the testes are four small 
plate-like masses of large cells attached to the anterior septa 
of somites x and x1, close to the nerve cord in a similar posi- 
tion to that of the ovary in somite x11. They can only be 
observed in a worm in which the clitellum is undeveloped. 
[In Microcheta the two pairs of testes exist in two 
pairs of horn-like, hollow prolongations of the anterior 
median part of the seminal reservoirs; these prolonga- 
tions have thick walls, and I think they are very probably 
permanent. ] 
The Seminal Reservoirs.—As a rule these are sac-like, 
more or iess compact, whitish bodies. 
In Titanus there is only a single pair of seminal reservoirs 
of the same general appearance as the two pairs in Lumbri- 
cus, but they are prolonged through twelve or fifteen somites 
on each side of the alimentary tract. [I shall describe another 
