The existing genera include Anas, Aquila, Bubo, Columba, Cypselus, Lanius, Picus, Phalacrocorax, Sula, &c. Very interesting is the fact that Serpentarius, Psittacus and Trogon are amongst this list of birds, which are now restricted to the tropics.
Between fifty and sixty so-called families of land birds alone are found within its limits, and of them at least nine are peculiar; the typical genera of which are Buphaga, Euryceros, Philepitta, Musophaga, Irrisor, Leptosoma, Colius, Serpentarius, Struthio, Aepyornis.
The unlookedfor discovery in France of remains which he has referred to, forms now existing it is true, but existing only in countries far removed from Europe, forms such as Collocalia, Leptosomus, Psittacus, Serpentarius and Trogon, is perhaps even more suggestive than the finding that France was once inhabited by forms that are wholly extinct, of which in the older formations there is abundance.
In this enumeration Serpens is included in Serpentarius and Lupus in Centaurus; these two constellations were separated by Hipparchus and, later, by Ptolemy.
The appearance, in September 1604, of a new star in the constellation Serpentarius afforded him indeed an opportunity, of which he eagerly availed himself, for making an onslaught upon the Aristotelian axiom of the incorruptibility of the heavens; but he continued to conform his public teachings in the main to Ptolemaic principles, until the discovery of a novel and potent implement of research in the shape of the telescope placed at his command startling and hitherto unsuspected evidence as to the constitution and mutual relations of the heavenly bodies.