Distribution.—The species seem distributed over the whole world, but as far as we can trust our present scanty materials, are most common in the warmer temperate regions. The S. vulgare ranges from the Norwegian seas to Naples. Most of the species are inhabitants of deep water.
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 Scalpellum, (excepting S. villosum and S. rutilum,) and destroy all the valves, but 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 Scalpellum and that genus.
Geological History.—Full details on this subject have been given in the Memoirs of the Palæontographical Society. I will here only state, that the oldest known form of Scalpellum occurs in the Lower Green Sand.
[† SUB-CARINÂ NULLÂ.]
1. Scalpellum Vulgare. [Pl. V], [fig. 15.]
![[Pl. V]](#475865927904411783_p05.png.id-4801275981916817250.wrap-0.html.html){kind=link}
![[fig. 15.]](#475865927904411783_p05f15.png.id-7120140256631762188.wrap-0.html.html){kind=link}
Scalpellum vulgare. Leach. Encyclop. Brit. Suppl., vol. iii, 1824.
Lepas Scalpellum. Linn. Systema Naturæ, 1767.
——— ————— Poli. Test. utriusque Siciliæ, Pl. vi., fig. 16. 1795.
Pollicipes Scalpellum. Lamarck. An. sans Vertebres, 1818.