DENDROSOMA RADIANS, EHRENBERG. 
145 
Material. 
The first material we examined was supplied to us some 
years ago by Mr. Bolton, of Birmingham. Since that time 
he has forwarded to us living specimens on several occasions. 
The Birmingham material is usually attached to water 
plants. 
A few years ago the Kev. T. Robinson, of Hale, informed 
us tliat Dendrosoma could be obtained in the Bridgewater 
canal, in the neighbourliood of Altrincham, attached to 
specimens of Cordylophora, and we have found it there 
and obtained an abundant supply at all times of the year. 
For many mouths it is principally attached to the hydrocauli 
of living Cordylophora, but we have also found it on the 
stalks of freshwater Polyzoa and on weeds. In the winter 
we have found specimens on the perisarc of the hydrocauli of 
Cordylophoras that have died down. It is noteworthy that we 
found these specimens a few days after the severe frost of Decem- 
ber 25th to doth, 1908. They were very pleutiful, healthy, 
and weie giving rise to a great many gemmulae. They were 
also provided with a considerable number of epizoic Urnulas. 
These facts seem to {irove that there is no special advantage 
gained by the Dendrosoma in being associated with the 
Cordylophora other than that of position. It seems probable 
also that Cordylophora gains no advantage by the presence 
of Dendrosoma on its hydrocauli. 
A difficulty in the investigation of the Dendrosoma found 
in the Bridgewater canal is, that the test becomes encrusted 
with a thick coat of Avhat we can only call black dirt (text- 
figs. A and B). This renders the observation of the structure 
of the stolon and the proximal regions of the arms in anything 
but sections extremely difficult. The material obtained from 
Birmingham is much cleaner. Associated with the Cordylo- 
phora and Dendrosoma in the Bridgewater Canal there are 
several other genera of Aciuetaria, Vorticella, Car- 
chesium, Epistylis, and Stentor, besides worms, 
Rotifers et hoc genus omne. 
