. 
INTRODUCTION. 5 
the lines of growth in their valves. Aptychus, according to M. D’Orbigny, existed during the 
Carboniferous system, at a period vastly anterior to the oldest known Pollicipes, yet on 
the idea of its having been a Cirripede, the growth of its valves (Scuta) must have been 
upwards, as in the most recent forms; and it was allied to Lepas, that genus which, in the 
order of creation, and in the manner of growth, stands at the opposite end of the series 
from Pollicipes. From the several reasons now given, it does not appear to me that 
Aptychus, until weightier evidence is adduced, can be safely admitted as a Cirripede. 
Geological History.—No true Sessile Cirripede’ has hitherto been found im any 
Secondary formation; considering that at the present time many species are attached to 
oceanic floating objects, that many others live in deep water in congregated masses, that 
their shells are not subject to decay, and that they are not likely to be overlooked when 
fossilized, this seems one of the cases in which negative evidence is of considerable value. 
Mr. Samuel Stutchbury, moreover, (to whom I am deeply indebted for much information, 
and the loan of his beautiful collection of recent species,) has assured me that vast numbers 
of fossil secondary corals have passed through his hands, and that he has carefully looked 
without success for those genera which commonly inhabit living corals. Sessile Cirripedes 
are first found in Eocene deposits, and subsequently, often in abundance, in the later 
Tertiary Formations. ‘hese Cirripedes now abound so under every zone, all over the 
world, that the present period will hereafter apparently have as good a claim to be called 
the age of Cirripedes, as the Palzeozoic period has to be called the age of Trilobites. There 
is one apparent exception to the rule that Sessile Cirripedes are not found im Secondary 
formations, for I am enabled to announce that Mr. J. de C. Sowerby has in his collection 
a Verruca (= Clisia, Clytia, Creusia, Ochthosia) from our English chalk: but this genus, 
though hitherto included amongst the Sessile Cirripedes, must, when its whole organisation 
is taken into consideration, be ranked in a distinct family of equal value with the Balanidee 
and Lepadidz, but perhaps more nearly related to the latter than to the Sessile Cirripedes. 
Hence the presence of Verruca in the Chalk is no real exception to the rule that Sessile 
Cirripedes do not occur in Secondary formations; on the contrary, it harmonises with the 
law, that there is some relation between serial affinities of animals, and their first appearance 
on this earth. 
The oldest known pedunculated Cirripede is a Pollicipes, discovered by Professor 
Buckman in the Stonesfield Slate in the Lower Oolite: two species of the same genus 
have been described by Mr. Morris from the Oxford Clay, in the middle Oolite. I have 
1 Dr. Petzholdt has described and figured (Jahrbuch, 1842, p. 403, tab. x), a Balanus carbonaria 
from the carboniferous system; but as neither the operculum, the structure of the shell, the number of 
the valves, nor their manner of growth, can be made out or are described, the evidence appears quite 
insufficient to admit the existence of this genus at so immensely a remote epoch. Bronn, in the ‘Index 
Palzontologicus,’ gives, under Tubicinella, a cretaceous species; I have unfortunately not been able to 
consult the original work cited. 
