DENDROSOJIA RADIANS, ElIKENBERG. 
171 
— and the measurements given bj Sand of tliis species are : 
Length of test, 20/i-120n ; diameter of test and body, 15g-80//; 
diameter of the nucleus, The genus is characterised 
by the definite but very thin test, which is usually conical in 
shape and curved proximally towards the disc of attachment. 
There are one, or two (rarely more than two) tentacles. The 
reproduction is by oblique unequal fission, and the smaller of 
the two products of fission escapes as a ciliate gemmula. 
The question whether the species of Urn u la we have found 
on Dendrosoma should be referred to the species U. episty- 
lidis or placed in a new species may be open to discussion; 
but we can find no satisfactory reasons at pre.sent for adopt- 
ting the latter course. 
The specimens attributed to U. epistylidis by Sand and 
other authors are very variable in size (15/<-80/t in body 
diameter), so that the fact that the largest of the specimens 
we have measured is not more than 30 /< in this diameter and 
the average is about 25 /x does not signify more than that the 
Urnula on Dendrosoma belongs to a small race. 
In the original figure given by Claparede and Lachmann 
the two tentacles are shown to arise from the side of the 
body turned towards the host. In most of our specimens the 
tentacles ari.se from the distal surface or apex, as shown in 
figs. 35-39. The oinginal figure with the tentacles arising 
from the sides has been copied in the subsequent papers and 
books, and it seems to be b}" no means certain that this 
origin is normal in the species. The body may rotate more or 
less in the test and the appearance shown may be only 
temporary, but we have observed only one or two cases in 
which the origin of the tentacles may have been lateral. 
3’he position of the contractile vacuole was not constant in 
our specimens. It is usually situated, as shown in figs. 35-39, 
near the centre of the distal convexity, but in several speci- 
mens we have seen it more deep-seated. In the figures of the 
species given by other authors it is shown by the outer side of 
the nucleus. The structure of the test, which is extremely 
delicate, appears to be the same as that previously described. 
