"A dark veil," says Lesson, "covers our knowledge of the Cetacea ; it is only by groping that we can follow this path strewn with thorns, and at a time when all other branches of natural science are being covered with flowers and fruit, cetology, reduced to meagre and shrivelled buds, many of which are sterile and sapless, leaves on our minds a most painful impression." It is generally acknowledged, that few orders of Vertebrata are established in a way which leaves so much to be desired, both as regards the distinction of species and the description of internal parts, as that of the whales. In these later times, several able naturalists have, however, paid considerable atten- tion to this subject, and have cleared up many a dark page penned by ancient writers, who, but too often, created species on insufficient grounds, such as the sayings of sailors, or the tales of voyagers and travellers, whose exaggerated reports led them to admit numberless errors into the annals of science. These errors, copied by others, with a few supplementary exaggerations and additions, have become still more faulty, and at present only serve to torture the naturalist who at- tempts to discover truth amidst a tissue of false and useless indi- cations.
No group of Mammalia has suffered more in this respect than the Cetacea ; as if the curious conformation, peculiar mode of life, and of- ten immense size of these monsters of the deep, were not sufficient in themselves to create universal astonishment; the older naturalists often filled up their bulky compilations with imaginary species which have no counterpart in nature, and most of their descriptions may be considered as purely fictitious, and ranged in our days amongst the many absurdities which were believed by our ancestors.
The difficulty of distinguishing truth from falsehood in a subject so intricate, is the reason why many animals which had been really ob- served years ago, but which have not reappeared since, have been placed (though often erroneously) among the imaginary or purely hypothetical species.
The Cetacea (excluding the Herbivora) may be divided into three groups.
1. Whales having a disproportionately large head and a dorsal fin.
2. Whales whose head is much produced, which have no dorsal fin.
3. Whales whose head is of an ordinary size.
The first of these groups comprehends two genera : —
