Page:Transactions of the Linnean Society of London, Volume 12.djvu/28

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All the insects of this family swim on their back, moving by means of their long hinder legs, which resemble oars; whence they have been aptly named boat-flies.

Besides the characters given in the above table, the following will be useful in order to enable the young entomologist to distinguish this genus from, from which it has not been separated by any entomologist.

The thorax is hexagonal, the anterior part is much attenuated, and the hinder margin is straight. The head is narrower than the broadest part of the thorax; the eyes are oblong, and converge a little behind; the hinder legs are much ciliated, and the claws are so minute as to be discovered with great difficulty; the tips of the elytra are notched.

N. elytris nigris, maculis duabus bascos griseis: posticâ majore.

Notonecta furcata.

''Fabr. Ent. Syst''. iv. 58. ''Syst. Rhyng.'' 102. 2. ''Oliv. Encycl. Méthod. Hist. Nat.'' viii. 388. 2.

Var. β. Elytris maculâ ferrugineâ.

Habitat in Caledoniæ, Angliæ aquis vulgatissime.

Elytra apice fuliginosa; dorsum nigrum.

N. elytris fusco ferrugineoque variis, dorso ferrugineo fasciâ mediâ pernigrâ.

Notonecta maculata.

''Fabr. Ent. Syst.'' iv. 58. ''Syst. Rhyng.'' 103. 4.

Rh