As regards the latter question, I have little doubt that the Sirenia connect the Ungulata with the proboscidea; and none, that the Cetacea are extremely modified Carnivora.
"Critiques and Addresses"
Thomas Henry Huxley
They are composed of tubular and convoluted portions of enamel filed up with dentine, and their worn surfaces show a variety of patterns, as in the case of the proboscidea.
"Natural History of the Mammalia of India and Ceylon"
Robert A. Sterndale
The order proboscidea, or animals whose noses are prolonged into a flexible trunk, consists of one genus containing two living species only-the Indian and African Elephants.
"Natural History of the Mammalia of India and Ceylon"
Robert A. Sterndale