In cormorants (Phalacrocoracidae), and especially in Sula, where the nasal slits become completely closed up, and the greater portion of the nasal cavity is also abolished, being restricted to the olfactory region with its unusually wide choanae.
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.
In Colorado and New Mexico Marsh has detected bones of Meleagris, Puffinus, Sula and Uria, all existing genera; but the first is especially suggestive, since it is one of the most characteristic forms of the New World.
Dvina, and the Pripet, both very important for navigation - as well as several smaller tributaries on which rafts are floated; on the left the Sozh, the Desna, one of the most important rivers of Russia, navigated by steamers as far as Bryansk, the Sula, the Psiol and the Vorskla.
The more common sea-birds are the Sula variegate or guano-bird, a large gull called the Larus modestus, the Pelecanus thayus, and the Sterna Ynca, a beautiful tern with curved white feathers on each side of the head.