56 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Just Subsequent to Anterior Moult . — Eight animals were immersed. 
Exact records were obtained in the case of six, thus 
Hours . 
13-14 
16-17 
24-25 
26-27 
28-29 
36-37 
No- of Animals . 
1 
1 
1 
1 
1 
Two others are recorded as having; died “ between 22 and 35 hours.” It 
will be noted that, whereas in the previous two sets of experiments no 
animals were known to survive beyond 21 hours, in the present set six 
out of eight, i.e. 75 per cent., lived over 22 hours. 
These results with moulting animals not only confirm the previous 
experiments but they perhaps indicate that just subsequent to complete 
moult a sudden increase in resistance to the deleterious effect of distilled 
water is established. 
General. 
There can be no doubt that the immediate ancestors of Ligia were sea 
animals. If this terrestrial stock had been derived through a fresh- water 
line, it would not be so susceptible to damage from immersion in dilute 
sea-water. The physiological method of inquiry bears out the inference 
hitherto drawn simply from the distribution of the genus. All the known 
species frequent the sea-sliore (see Stebbing (3)). 
The question regarding its invariable occurrence in suitable localities,* 
conjoined with its complete absence from other localities (often miles in 
extent) along the shore, is no longer such a puzzle. It is quite open to 
suppose that the animal is carried past impassable areas by means of 
floating drift-material (the clinging habits of the creature must be kept 
in mind). 
From the literature it is hard to extract a definite statement as to 
whether Ligia normally enters the sea. While collecting supplies for 
experiments the author paid particular attention to this point. Numerous 
pieces of evidence, all pointing in the same direction, were obtained. Large 
communities of Ligia were found completely immersed under stones that 
rested in supra-tidal saline pools. Heaps of stones, apparently too dry for 
permanent habitation, were discovered to be densely populated if in the 
immediate neighbourhood of such semi-permanent pools. Specimens on 
* According to tlie observations of the writer, a “ suitable locality implies deeply 
fissured rock, or heaps and slabs of broken angular stone large enough to afford permanent 
dampness underneath. Ligia is not found among sand ; nor among decaying weed ; nor 
among stones, whether large or small, that are subject to frequent displacement by 
the waves. 
