Royal Microscopical Society. 
53 
Three hemispherical cushions (as in Hydatina) crown the head ; 
and the setm on them, Fig. 3, have distinct bases from which they 
spring, and through which they grow. In the young Notommata 
only the tip of each seta can be seen just above the top of its cylin- 
drical base. Similar partly sheathed cilia are to be seen ranged 
parallel to one another on each side of the buccal funnel ; an en- 
larged view of these is given at Fig. 4, which also shows a fan of 
small setae situated just above the base of each of the larger ones. 
At the bottom of the funnel also are large curved cilia (figured at (a) 
in Fig. 2), and I have more than once thought that I could detect 
the presence of minute cilia over the whole surface of the cavity. 
I have added to the Plate, Fig. 7, the male of a new species 
of Asplanchna. The female resembles Asplanchna priodonta, but 
differs from it in having an unusually large contractile vesicle, 
which is kept constantly in motion to and from the ovary with a 
sort of semi-contraction, but without the distinct spasmodic col- 
lapse that usually characterizes this organ. The vibratile tags too 
are numerous, and arranged in a long straight fine down the whole 
length of the body, as in A. Brightwellii. It is, however, only 
half the size of A. Brightwellii, and its peculiar male also shows it to 
be a different species. I should have thought it to be A. Sieboldii, 
were it not that the male of A. Sieboldii has four arm-like processes, 
and this male has only two. The male is wonderfully transparent 
and empty ; for such organs as it has are small, and its skin is so 
delicate that it is often difficult to detect the creature in the water 
with a lens, in spite of its being of the respectable size of -g^th of an 
inch. Its two arms ( d ) and an odd hump (e) are only seen when 
it retracts its head ; on doing this they start out stiff from the 
body in the most comical fashion, and collapse again as the relax- 
ing muscles allow the head to resume its usual position. The 
atrophied oesophagus is seen at (e) attached by a thread to the 
conical hump : of the mastax, stomach, or salivary glands, there is 
not a trace. The vibratile tags and contractile vesicle are as well 
seen as in the female, but I have met with a specimen in which the 
tags appeared to be quite empty, with the exception of two or 
three near the contractile vesicle in which the usual cilia were 
vibrating. 
It is hardly possible to consider so rudimentary a creature as 
this male Asplanchna without speculating on the steps that have 
brought it into so strange a condition. When we find an atrophied 
oesophagus, closed at both ends, without either mastax or stomach 
attached to it, but in precisely the same position as the oesophagus 
of the female, it is difficult to imagine that we are looking at the 
original state of things : the mind naturally pictures to itself a time 
when the oesophagus was of real use, when it led from a mouth to 
a stomach, and when the male, as capable of feeding as the female, 
