In my essay on Whales in the ‘Zoology of the Erebus & Terror,’ 1846, I separated the Right Whales, or Balænidæ, into two divisions—the one having very slender, long, polished whalebone with a single series of fringe, and the second with coarser, shorter, and broader whalebone and a thick coarse fringe. The first was afterwards called _Balæna_, and the second _Eubalæna_. M. Beneden seems inclined to adopt this division (see ‘Ostéographie,’ Cétacés, p. 144), observing that the former are confined to the Arctic regions and the other to the more temperate zones; but this is not correct, for _Balæna marginata_, as I stated in my first essay, has the whalebone quite as polished and as fine as that of the Greenland Whale. It lives on the west coast of Australia and New Zealand, in company with the Black Whale of Australia and the Black Whale of New Zealand (both of which, I have no doubt, have short coarse whalebone). The Whale of the most northern parts of the Pacific yields the north-west-coast whalebone, which is of a very coarse character. The first section of Whales, with long, slender, elastic, polished, finely fringed whalebone, contains two genera, _Balæna_ and _Neobalæna_. The Whales of the second section, which have rough, brittle whalebone, with a thick fringe of coarse hairs, includes four genera, viz. _Eubalæna_, _Hunterius_, _Caperea_, and _Macleayius_. It is very true that I have only seen the whalebone in one of these genera, _Eubalæna_, in connexion with the bones of the animal; but as “the South-sea whalers” (that is to say, those who fish in the Southern and Pacific oceans) have only brought various examples of this kind of whalebone from any of their voyages (except a few blades of the whalebone of _B. marginata_, which they call “sea-tassel”), we may naturally conclude that all the large Right Whales found in those seas have this kind of whalebone. Suborder I. BALÆNOIDEA (_cf._ p. 46). Head large. Body stout. Dorsal fin none. Chest and belly smooth, without plaits. Pectoral fin broad, truncated; fingers 5, graduated. Arm-bones very short, thick; radius and humerus of equal length. Baleen elongate, slender. Tympanic bones rhombic. Cervical vertebræ united. Balænoidea, _Gray_, _Synops. Whales & Dolph._ p. 1. Family 1. BALÆNIDÆ. _Right Whales._ Balænidæ, _Gray_, _Cat. Seals & Whales B. M._ pp. 61, 75; _Synops. Whales & Dolph._ p. 1; _Lilljeborg_, _N. Acta Upsal._ 1867, vi. Head very large, and body short. Dorsal fin none. Belly smooth. Baleen elongate, slender. Vertebræ of the neck anchylosed. Pectoral fin broad, truncated at the end; fingers 5. Tympanic bones rhombic; maxillary bones narrow.