VERRUCA. 4] 
Genus—VERRUCA. 
Verruca.! Schumacher. Essai d’un Nouveau Syst. Class., 1817. 
Cuysta. Leach. Journal de Physique, tom. 85, July, 1817; Clisia, Leach, Encyclop. 
Brit. Suppl., vol. iii, 1824; Clitia, G. B. Sowerby, Genera of Recent and 
Fossil Shells. 
Creusia. Lamarck. Animaux sans Verttbres, 1818. 
OcutHosia. Ranzani. Memoire di Storia Nat., 1820. 
Lepas ET BaLANuSs AUCTORUM. 
The family of Verrucide includes only the above single genus; but it has, I think, as 
good a claim to be considered a distinct Family as either the Balanide or Lepadide, that 
is, either the Sessile or Pedunculated Cirripedes. ‘The two latter Families differ from each 
other almost exclusively in the nature of the shell or external covering, and in the 
muscles moving the different portions of it: now Verruca has a very peculiar shell, 
destitute of all muscles, excepting the adductor scutorum, and composed of only six 
valves, and these are so unequally developed, that the longitudinal dorso-ventral plane of 
the body comes to lie nearly parallel to the surface of attachment, instead of at right angles 
to it. Upon the whole, the Verrucide are nearly equally related to the Lepadidz and 
Balanide ; but certainly nearer to the Lepadide, than to the sub-family Balanine or typical 
sessile cirripedes ; though, on the other hand, if compelled to place Verruca in one of 
these two Families, I should place it amongst the Chthamaline, the other sub-family of 
Balanide. The distinctness of Verruca, though in appearance a sessile cirripede, from 
the Balanidze or true sessile cirripedes, is interesting, masmuch as no member of this latter 
Family has hitherto been found fossil in any Secondary Deposit, whereas Verruca ranges 
from the present day to the upper beds of the Chalk near Norwich, and in Belgium ; 
being likewise found in the Glacial Deposits, in the Red and Coralline Crags of England, 
and in an ancient tertiary formation of Patagonia. 
The shell of Verruca has generally been quite misunderstood: it consists, as already 
stated, of six valves; and these can be proved (as I have shown in my volume published 
by the Ray Society), by tracing the development of the young shell, to consist of a rostrum 
and carina, unequally developed on their two sides,—of a scutum and tergum in their 
normal and moveable condition,—and, lastly, of the scutum and tergum on the opposite 
side, most singularly modified, immoveably articulated to the rostrum and carina, forming 
together with them a shell, which is firmly united to the basal membrane, and so to the 
surface of attachment. It can be shown that the very remarkable modification and 
1 According to Bock, in the ‘ Naturforscher’ of 1778, this term was used by Rumph for a Chelonobia, 
but as it was before the adoption of the binomial nomenclature, according to the Rules, it may be passed 
over, and does not interfere with the priority of Schumacher. 
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