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FROM ARISTOTLE UNTO THIS DAY 203 
The first pair of trunk-legs are large, robust, markedly un- 
equal. The type-species is Astacus gammiéarus (Linn.), which 
Milne-Edwards and Bell speak of as Homarus vulgaris. 
Occasionally this is corrected by authors into Homarus 
gammarus. Spence Bate admits that Leach has un- 
doubted priority, but regrets that to acknowledge his 
claim would only have the result of creating great con- 
fusion, which Leach himself would have deprecated, and 
that it would introduce terms not likely to be generally 
accepted. ‘The sentimental consideration that Dr. Leach 
would deprecate a particular result may be dismissed, 
since in natural history the author of a name once pub- 
lished has no more control over it than any other person. 
In the due recognition of priority there is probably a 
better chance than any other principle affords of eventually 
clearing away confusion. No doubt, to our eyes, the age 
of Leach, as far as Crustacea are concerned, seems a kind 
of primitive antiquity, but in the perspective of another 
century or two the writers of to-day will seem to stand 
close by his side or very little in front, and if our nomen- 
clature is carried out without principle, we must expect to 
be treated like the pre-Linnzan zoologists, and have our 
nomenclature put altogether out of court. It may be 
mentioned that Adam White, a considerable authority in 
his time, uses the name Astacus gammarus for the lobster, 
in his ‘Popular History of British Crustacea,’ published 
in 1857, thus showing that he was not to be daunted or 
Jed astray by the authority either of Milne-Edwards or of 
Bell. Leach remarks that ‘ Aristotle has very distinctly 
described this species under the name aotaxos.’ He is 
referring no doubt to the very interesting but rather per- 
plexing second chapter of the fourth book of Aristotle’s 
‘ History of Animals.’ 
Astacus americanus (Milne-Edwards) closely resembles 
the European species, but has two spines on the under 
surface of the rostrum, which are wanting in its congener. 
It is, like the other, a large and extremely prolific species, 
much sought after for food. It is reckoned that a million 
a year are consumed in Boston alone. Professor 8. I. 
