VERRUCA. 41 



Genus — Verruca. 



Verruca.' Schumacher. Essai d'un Nouveau Syst. Class., 181". 



Clysia. Leach. Journal de Physique, torn. 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 Vertebres, 1818. 

 Ochthosia. Ranzani. Memoire di Storia Nat., 1820. 

 Lepas et Balanus Auctorum. 



The family of Verrucidse includes only the above single genus ; but it has, I think, as 

 good a claim to be considered a distinct Family as either the Balanidae or Lepadidse, 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 Verrucidee are nearly equally related to the Lepadidse and 

 Balanidae ; but certainly nearer to the Lepadidse, than to the sub-family Balaninse 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 Chthamalinae, the other sub-family of 

 Balanidae. The distinctness of Verruca, though in appearance a sessile cirripede, from 

 the Balanidae or true sessile cirripedes, is interesting, inasmuch 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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