. Guide leaflet. REPTILIANThe forerunners of the mammalian earossicles as they lie in the reptile columella is indicated by horizontalhatching; the quadrate by stippling, thearticular by vertical lines. MAMMALIAN The ear ossicles of mammals. The stapes is the equivalent of the columella, the incus is derived from the quadrate, and the malleus from the articular In almost all mammals there are seven cervical vertebrae. In the giraffethese are excessively elongated and in the whales excessively com-pressed. Only in the manatee (21) and a species of two-toed sloth (16)is the number redu
. Guide leaflet. REPTILIANThe forerunners of the mammalian earossicles as they lie in the reptile columella is indicated by horizontalhatching; the quadrate by stippling, thearticular by vertical lines. MAMMALIAN The ear ossicles of mammals. The stapes is the equivalent of the columella, the incus is derived from the quadrate, and the malleus from the articular In almost all mammals there are seven cervical vertebrae. In the giraffethese are excessively elongated and in the whales excessively com-pressed. Only in the manatee (21) and a species of two-toed sloth (16)is the number reduced to six and only in the three-toed sloths is thenumber increased, here to nine. The mammals develop bony ends or epiphyses on the limb bones(rare in reptiles) and on the vertebrae. It is between these epiphyses and BIOLOGY OF MAMMALS 7 the shafts of the bones that growth in length takes place. When thesutures between them close growth stops (23J. The limbs of mammals are more efficiently constructed for rapid andsustained locomotion than are those of the other quadrupedal landvertebrates. The legs are brought more directly under the body, thelength of the bones is usually increased and the joints tend
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectnatural, bookyear1901
