at it would
be superfluous here to repeat the same list of authors. I will only add,
that since the date, 1834, of the above works, the only important papers
with which I am acquainted, are, 1st. Dr. Coldstream 'On the Structure
of the Shell in Sessile Cirripedes,' in the 'Encyclopaedia of Anatomy and
Physiology;' 2d. Dr. Loven 'On the Alepas squalicola,' ('Ofversigt of
Kongl. Vetens.,' &c. Stockholm, 1844, p. 192,) giving a short but
excellent account of this abnormal Cirripede; 3d. Professor Leidy's very
interesting discovery, ('Proceedings of the Academy of Natural
Sciences,' Philadelphia, vol. iv, No. I, Jan. 1848,) of eyes in a mature
Balanus; 4th. Mr. A. Hancock's Memoir, ('Annals of Natural History, 2d
series, Nov. 1849,) on his Alcippe lampas, the type of a new order of
Cirripedes; 5th. Mr. Goodsir's Paper, ('Edinburgh New Philosoph.
Journal,' July 1843,) on the Larvae in the First Stage of Development in
Balanus; 6th. Mr. C. Spence Bate's valuable Paper on the same subject,
lately published, (Oct. 1851,) in the 'Annals of Natural History;' and
lastly, M. Reinhardt has described, in the 'Copenhagen Journal of
Natural History, Jan. 1851,' the _Lithotrya Nicobarica_, and has
discussed its powers of burrowing into rocks.

I have given the specific or diagnostic characters, deduced from the
external parts alone, in both Latin and English. As I found, during the
progress of this work, that a similarly abbreviated character of the
softer internal parts, was very useful in discriminating the species, I
have inserted it after the ordinary specific character.

In those cases in which a genus includes only a single species, I have
followed the practice of some botanists, and given only the generic
character, believing it to be impossible, before a second species is
discovered, to know which characters will prove of specific, in
contradistinction to generic, value.

In accordance with the Rules of the British Association, I have
faithfully endeavoured to give to each species the first name attached
to it, subsequently to the introduction of the binomial system, in 1758,
in the tenth edition[1] of the 'Systema Naturae.' In accordance with the
Rules, I have rejected all names before this date, and all MS. names. In
one single instance, for reasons fully assigned in the proper place, I
have broken through the great law of priority. I have given much fewer
synonyms than is usual in conchological works; this partly arises fro