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IV. Some Account of the Crustacea of the Coasts of South America, with Descriptions of 
new Genera and Species: founded principally on the Collections obtained by Mr. Cuming 
and Mr. Miller. By Tuomas Bett, Hsq., F.R.S., L.S8., G.S., & ZS. 
Communicated November 10, 1835. 
THE rich acquisitions which have accrued to science from the indefatigable exertions 
of Mr. Cuming have already furnished matter for numerous communications to the 
Zoological Society, which have hitherto been principally devoted to the description of 
new species of Mollusca, or to the anatomical structure of animals of the same great 
group. The collection of Crustacea procured by the same gentleman, amounting to 
about one hundred and fifty species, promised to afford many new forms; and it was 
at first my intention to content myself with the description of such new genera and 
species as were contained in that collection. Finding, however, that in some particular 
genera the new species were either so numerous, or so interesting and important in their 
characters, as to throw an entirely new light upon the character of the groups to which 
they belonged, and having these means of information enlarged by the kindness of my 
friend Mr. Miller, who has, with his usual liberality, presented me with the whole of a 
small collection made by him principally on the coast of Brazil, I have been induced to 
extend my original plan, by embodying an account of the whole of the species collected 
by these gentlemen ; and offering, in a few instances, monographs of such genera as 
require an entirely new arrangement, or new distinctive characters, in consequence of 
these acquisitions. In furtherance of this object I have already communicated to the 
Zoological Society, a monograph of the restricted genus Cancer, enriched by no less 
than three new and highly interesting species'; and I now proceed to offer the further 
detail of the contents of these collections in a systematic form, commencing with the 
Oxyrhynchi. 
The arrangement which I have adopted is generally that of Dr. Milne Edwards, whose 
work on the natural history of Crustacea is not only by far the most complete that has 
ever appeared, but offers a classification which, though not free from some inconsiderable 
objections, yet, as being founded upon structural rather than mere formal characters, 
must be allowed to constitute the nearest approach hitherto made to a natural arrange- 
ment. 
' Trans. Zool. Soc., vol. I., p, 335. 
