m
my conviction that giving references to works, in which there is not any
original matter, or in which the Plates are not of a high order of
excellence, is absolutely injurious to the progress of natural history,
and partly, from the impossibility of feeling certain to which species
the short descriptions given in most works are applicable;--thus, to
take the commonest species, the _Lepas anatifera_, I have not found a
single description (with the exception of the anatomical description by
M. Martin St. Ange) by which this species can be certainly discriminated
from the almost equally common _Lepas Hillii_. I have, however, been
fortunate in having been permitted to examine a considerable number of
authentically named specimens, (to which I have attached the sign (!)
used by botanists,) so that several of my synonyms are certainly
correct.

[1] In the Rules published by the British Association, the 12th
edition, (1766,) is specified, but I am informed by Mr.
Strickland that this is an error, and that the binomial method
was followed in the 10th edition.

The Lepadidae, or pedunculated Cirripedes, have been neglected under a
systematic point of view, to a degree which I cannot quite understand:
no doubt they are subject to considerable variation, and as long as the
internal surfaces of the valves and all the organs of the animal's body,
are passed over as unimportant, there will occasionally be some
difficulty in the identification of the several forms, and still more in
settling the limits of the variability of the species. But I suspect the
pedunculated Cirripedes have, in fact, been neglected owing to their
close affinity, and the consequent necessity of their being included in
the same Work with the Sessile Cirripedes; for these latter will ever
present, I am fully convinced, insuperable difficulties in their
identification by external characters alone.

I will here only further remark, that in the Introduction I have given
my reasons for assigning distinct names to the several Valves, and to
some parts of the included animal's body; and that in the Introductory
Remarks, under the general description of the Lepadidae, I have given an
abstract of my Anatomical Observations.

CORRIGENDA AND ADDENDA.

Page

12, twenty lines from bottom, _for_ "hinder pair of true thoracic
limbs," _read_ "pair of true thoracic limbs."

42, 43. I should have added, that the number of the segments in