150 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Pelagic Turbellaria are rare, but occasionally occur in 
tow-nettings. Such are certain Rhabdoceeles and larval 
Polyclads. 
TURBELLARIA,. 
I.—TRICLADIDA. 
1. Planaria alpina, Dana (Pl. XII, figs. 1 and 2.) 
This fresh-water species 1s about }" in length, body 
erey, produced anteriorly into a pair of tentacles, a single 
pair of eyes are present. I have found it in cold springs 
near Silverdale (Lancashire) and in the sheltered gorges 
near Port Erin. This last fact taken in connection with 
Wm. Thompson’s discovery of alpina on the Hast coast 
of Iveland (which however needs confirmation) have an 
important bearing on the geographical distribution of this 
Turbellarian. Planaria alpina is a distinctly alpine 
creature and where occurring at lower levels, does so in 
water of a constantly low temperature. Dana first found 
it in the Graubuntner Alps. It has since been found near 
Chur and in the Davos mountains at heights of 6—7000 
feet and in water at a temperature of 2°C which is frozen 
from November to May. vv. Kennel (in a most interesting 
paper, (Zoologische Jahrbucher, III, p. 447), to which I 
am greatly indebted) has found it in the Maine Valley at 
Wurzburg at the outflow of a spring (temperature 10°C). 
The effect of a higher temperature than this is readily 
seen when attempts are made to keep these animals 
indoors. As soon as the water rises above 12°C they die 
very rapidly. 
With these facts in mind v. Kennel has attempted their 
explanation. The difficulty is this, how did Planaria 
alpina get from Switzerland to Wurzburg, England, 
the Isle of Man and Ireland? The tendency to explain 
this and similar cases by saying that alpina is a “‘ Relickt- 
ne 
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