Crossword-Solution: SIRENIA 7 letters, 6 clues 🏆 scrabble score: 7

The Sirenia form a very distinct group of the mammals, and one of the most remarkable peculiarities in existing dugong and lamentin is the entire absence of hind limbs, without even a rudiment being left; but the extinct Halitherium had, according to Professor Flower, an ossified thigh-bone “articulated to a well-defined acetabulum in the pelvis,” and it thus makes some approach to ordinary hoofed quadrupeds, to which the Sirenia are in other respects allied.

Whales and porpoises (Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and this may be advantageous to them for gliding through the water; nor would it be injurious to them from the loss of warmth, as the species, which inhabit the colder regions, are protected by a thick layer of blubber, serving the same purpose as the fur of seals and otters.

Moreover, I pointed out that as these Cetacea and Sirenia are certainly modified land animals, their existence implies the antecedent existence of land mammals.

Craniota (with skull) _a._ Cyclostomes (“round-mouthed”) _b._ Fishes Selachii Ganoids Teleosts Dipneusts _c._ Amphibia _d._ Reptiles _e._ Birds _f._ Mammal Monotremes Marsupials Placentals: Rodents Edentates Ungulates Cetacea Sirenia Insectivora Cheiroptera Carnassia Primates (This classification is given for the purpose of explaining Haeckel’s use of terms in this volume.

Leaving out of consideration the structure of the internal organs, they have teeth implanted in sockets in the jaws, four limbs, and a hairy covering to the skin, so that they possess more decidedly mammalian characters than some other members of the class, such as the marine whales and dolphins (_Cetacea_) and manatees (_Sirenia_), which are still often spoken of as fishes.