222 SCALPELLUM VULGARE. 



Affinities. — In the preliminary remarks, we have seen 

 how this genus blends into Pollicipes ; and under the 

 head of Oxynaspis, I have shown its close affinity to 

 that genus. If, indeed, we take Pollicipes spinosus, and 

 destroy all but six of the already minute and almost 

 rudimentary latera, we shall, as far as the capitulum 

 is concerned, convert it into a Scalpellum, closely 

 similar to S. villosum. If we take any species of Scal- 

 pellum, (excepting S. villosum and S. rutilum,) and destroy 

 all the valves, bat the scuta, terga and carina, we shall 

 convert it into an Oxynaspis. Lastly, I have shown 

 under Ibla, that in several most remarkable peculiarities 

 of structure, there is a manifest affinity between Scal- 

 pellum and that genus. 



Geological History. — Full details on this subject have 

 been given in the Memoirs of the Palseontographical 

 Society. I will here only state, that the oldest known 

 form of Scalpellum occurs in the Lower Green Sand. 



[f SUB-CARINA NULLA.] 



1. Scalpellum Vulgare. PL V, fig. 15. 



Scalpellum vulgare. Leach. Encyclop. Brit. Suppl., vol. iii, 



1824. 



Lepas Scalpellum. Linn. Systema Naturae, 1767. 



— Poli. Test, utriusque Siciliae, PI. vi., fig. 10. 



1795. 



Pollicipes Scalpellum. Lamarck. An. sans Vertebres, 1818. 



Polylepas vulgare. Be Blainville. Diet. Sc. Nat., Plate, 



fig. 4. 1824. 

 Scalpellum l^eve, var. Leach. Zoolog. Journal, vol. ii, p. 215, 



1825. 

 — SiciLLffi, var. Chenu. Illust. Conch. PI. iv, fig. 9. 



Scalpellum vulgare, (et var.) Brown. Illust. of Conch., 1844, 



PL li, figs. 7 to 20. 



S. (Hem.) valvis 14, si rostrum p eerie rudimentale 

 includatur : lateribus superioribus incequaliter ovatis. 



