ANATOMY OF LIMNOOCNIDA TANGANYICA. Kis 
gives rise to a number of strong circular muscle-bands, which 
may be seen in transverse sections to project into the meso- 
gloea. Near the point of attachment of the velum, the muscle- 
bands are small with a simple semicircular transverse section, 
but as they approach the free margin of the velum, they be- 
come larger and their transverse sections lobulated. From 
this it appears that the muscle-bands near the free edge of the 
velum are those which are chiefly concerned in the contraction 
of the organ. 
Nervous System.—No trace of a nervous system could 
be observed in transverse sections, although special search was 
made for a nerve-ring in the neighbourhood of the base of the 
velum. 
Sense-Organs.—The sense-organs or marginal bodies are 
embedded on the velar side of the zone of ectoderm which 
constitutes the nettle-ring. In all the individuals examined 
no relation could be demonstrated between the arrangement 
of the marginal bodies and that of the tentacles, though it is 
not improbable that some radially symmetrical disposition may 
occur in younger stages. It would seem that new marginal 
bodies are continually being developed, as even in the oldest 
individual examined quite young sense-buds were observed. 
In my former paper I suggested that the marginal bodies 
would be shown to be endodermal in origin, from the analogy 
of the corresponding organs in Limnocodium. It can now 
be definitely affirmed that the axial part of these organs is also 
of endodermal origin in Limnocnida. In Pl, 18, figs. 1 and 
2, there are figured two sections passing through a young mar- 
ginal sense-organ (4). It will be seen that the mesogleea 
(ms.), which is present almost everywhere between the ecto- 
derm of the nettle-ring and the endoderm of the circular canal, 
is broken through just beneath the base of the young sense- 
organ, and certain endoderm cells project from the endoderm 
into the young sense-bulb. In fig. 1, v. is such an endoderm 
cell actually wandering from the endoderm to take up its 
place in the axis of the sense-organ. The direction of move- 
ment is indicated by the edges of the perforation in the 
