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 PoUicipes, 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 PoUicipes, 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 in 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 hkely to be overlooked when 

 fossihzed, 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. These 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 Palaeozoic period has to be called the age of Trilobites. There 

 is one apparent exception to the rule that Sessile Cirripedes are not found in 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 Balanidse 

 and Lepadidse, 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 PoUicipes, 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. Petzlioldt has described and figured (Jahrbuch, 1842, p. 403, tab. x), a Balanus carhonaria 

 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 

 Palseontologicus,' gives, under Tubiciuella, a cretaceous species ; I have unfortunately not been able to 

 consult the original work cited. 



