TRANSACTIONS ENTOMOLOGICAL SOCIETY LONDON. I. DytiscidcB Darwiniance ; or, Descriptioiis of the Species q/" Dy tiscidse collected Z*?/ Charles Darwin, Esq., M.A. Sec. G. S. Sfc, in South America and Australia, during his Voyage in H.M.S. Beagle. ^?/ Charles C. Babing-TON, M. A., F. L. S., F. G. S., ^c. [Read 4th June, 1838,] At the request of my friend Mr. C. Darwin, I have examined the species oi Dytiscidce collected by him during his voyage with Captain Fitzroy in the Beagle, and have now the honour of sub-mitting the following descriptions of them to the Entomological Society. The specimens described very closely resemble some of those which are natives of the British isles : but, after a minute examination, a marked difference is always found to exist between them and any European insects. Before proceeding to the descriptions, I propose to make a few observations ; and in the first place I would draw attention to the Cybister, which I have named 2-imgulatus. It has been observed by Erichson, Curtis, Stephens, &c., that this genus has only one immoveable claw to the posterior tarsi. Hei-e (PI. I. fig. la, \ h) we find two clearly distinguishable claws both immoveable, and apparently joined together at their base ; or rather perhaps we ought to consider it as one claw very deeply divided into two parts. This insect also differs from the usual structure of the VOL. III. B
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