176 
sense of the term, would explain their diversity. Knowing, 
however, from his own observations what is meant by the 
statement that the Foraminifera are liable to great variation, 
he was prepared to say that the shells of the Marine Entomo- 
straca do not at all show this liability ; the forms are clearly 
defined, and distinct from one another, and intermediate 
forms blending the characters of two others rarely if ever 
occur. 
Then as to the last objection which was brought forward, 
namely the difficulty of defining what a species is, he believed 
that practically it might be put aside altogether ; for the 
fact was that any creature whatever which could be shown to 
be clearly distinct from all others that had been described 
must be admitted as a species, and must remain a species 
until it could be proved to be unworthy of this distinction. 
In conclusion he would say that he had no strong opinion as 
to whether this question of what a species is could or could 
not be answered, but he felt sure that to take Prof. William- 
son’s suggestion, and merge some ten or twenty of these 
forms of Marine Entomostraca into one species would be to 
make it impossible to form even a conjecture of what is 
meant by that term. 
A Paper was read “ On the Chsetopod Annelides of the 
Southport Sands,” by Benj. Carrington, M.D. 
Amphinomad^e. 
Aphrodite aculeata , L. Found sparingly near low-water 
mark ; more frequent after storms. 
Pholoe inornata , Johns. Very rare. 
Polynoa squamata , Sav. Found occasionally within old 
shells; frequent among oysters, and the refuse from the 
fishing boats. 
There are two well-marked varieties : 
a. with a dark-brown crescentic mark on each of the 
elytra. 
