146 SYDNEY J. HICKSON AND J. T. WADSWORTH. 
Of the other genera of these Aciuetaria, two ai’e of con- 
siderable importance in relation to Dendrosoma. These are 
the genera Trichophrya (Clap, and Lach.) and Leruaeo- 
phrya (Perez). 
At one period in our investigations we weie inclined to 
believe that both these genera represent young phases in the 
life-history of, or varieties of, Dendrosoma radians, butwe 
have since arrived at the definite conclusion that they are 
certainly distinct species. The relation between the three 
forms will be discussed later on, but we may state here that 
we are in ag'reement with Perez in considering Lernceo- 
phrya an intermediate form connecting Trichophrya with 
Dendrosoma and justifying the inclusion of the tlu'ee genera 
in the distinct family the Dendrosomina (Biitschli). It is a 
matter of considerable interest that the three closely allied 
genera should be found associated together in this manner in 
the same locality. The struggle for existence between the 
different Acinetaria and Ciliata must be very keen, and it is 
surprising that the three genera should have suiwived side by 
side. In the material from Birmingham we found no examples 
of either Trichophrya or Lernseophry a. 
The specimens from the Bridgewater canal consist of an 
irregular base or stolon attached to the perisarc of the host 
from which a number of free branches or ‘‘arms” project at 
various angles into the water (text-hg. A). It is difficult to 
form any vei-y definite conception as to the size to which a 
single individual may attain, as the stolon is usually so thickly 
encrusted with dirt of vailous descriptions, and bends so 
frequently from one side of the C'ordylophora to the other in 
its sinuous course, that the limits of the individual are often 
impossible to determine. We have measured single un- 
branched arms of this form that are ’5 mm. in length (text- 
fig. B). The tentacles are very extensile, and may be 75- 
90 fi in length. The arms arise from the stolon at irregular 
intervals, sometimes in clusters of three or four, sometimes at 
intervals of one or two millimetres. There appears to be no 
geometric law governing the origin of the arms ; but an arm 
