VERST 200 VEBTUE of 10 syllables, or in English in five ac- cented syllables, constituting five feet. VERST, a Russian measure of length, equal to 3,500 English feet, or very near- ly two-thirds of a mile. VERTEBRA, in comparative anatomy, one of the bony segments of which the spine, or backbone, consists. Theoreti- cally, a typical vertebra consists of a central piece or body, from which two arches are given off, one (the neural), protecting the nervous system, the other (the hsemal) protecting the organs of circulation, and thus corresponding to the doubly tubular structure of the body '>f the Vertebra. In practice the second arch is only recognizable with difficulty, the parts being either absent or much modified, but a good example may be seen in the human thorax. The fundamental element of each vertebra is the body or centrum, from the surface of which spring two bony arches, called the neural arches, or neurapophyses, because they form with the body the neural canal, which incloses the spinal cord. From the point of junction there is usually developed a spine, called the spinous process, or neural spine, rudimentary in the atlas or first cervical vertebra. From the neural arches are also developed the articular process or zygapophyses, which aid the centra in uniting the vertebrse to each other. From the sides of the body proceed the transverse processes. The number of vertebrae varies greatly in different animals. The vertebral col- umn is divisible into distinct regions, of which the following are recognizable in the higher Vertebrata: The cervical vertebrae (seven in man) , composing the neck; the dorsal (twelve in man), usually carrying well-developed ribs; the lumbar (five in man). These form the cervical, dorsal and lumbar regions respectively, and are sometimes called true vertebrae, to distinguish them from the false ver- tebrae, which consists of those in the sa- cral region usually anchylosed to form a single bone, the os sacrum, and a variable number of vertebrae forming the caudal region or tail. The spaces between the vertebrae are filled with an elastic substance, admitting of an amount of motion which, though slight between each pair, is in the aggregate sufficient to give the spinal column con- siderable flexibility. The vertebrae and their projections or processes afford at- tachments for a number of muscles and ligaments, and passages of blood ves- sels and for the nerves passing out of the spinal cord. VERTEBRATA, in zoology, a division of the animal kingdom, instituted by La- marck, comprising animals in which th« body is composed of a number of defi- nite segments, arranged along a longitu- dinal axis; the nervous system is in it§ main masses dorsal, and the neural and haemal regions of the body are always completely separated by a partition; the limbs are never more than four in num- ber ; generally there is a bony axis known as the spine or vertebral column, and a notochord is always present in the em- bryo, though it may not persist in adult life. A specialized haemal system is pres- ent in all, and in all but Amphioxus there is a heart with never less than two chambers, and in the higher verte- brates with four. The vertebrata are usually divided into five classes: Pisces, Amphibia, Reptilia, Aves and Mammalia, and many attempts have been made to gather these classes into groups. One plan is to divide them into branchiata (fishes and amphibians), because at some portion of their life they are pro- vided with gills, and abranchiata (rep- tiles, birds and mammals), having no gills. The latter are sometimes called amniota or allantoidea, because the em- bryo is provided with an ammon and an allantois, while both these are absent in the branchiata, which are therefore called anamniota or anallantoidea. Owen made two sections: Haematocrya, or cold-blooded vertebrates (fishes, am- phibia and reptiles), and Haematother- ma, or warm-blooded vertebrates (birds and mammals) ; and Huxley three: Ich- thyopsida (fishes and amphibia), saurop- sida (reptiles and birds), and mammalia. A later classification is to treat all the vertebrata as a division of a larger group, Chordata, distinguished by (1) tempo- rary or permanent possession of a rod (the notochord) underlying the central dorsally-placed nervous system; and (2) the temporary or permanent presence of visceral clefts. The Chordata are divided into three groups: (1) cephalochordata, in which the notochord, pointed at the extremities, extends from one end of the body to the other; (2) urochordata, and (3) the true vertebrata, or craniata, in which the anterior end of the central nervous system is enlarged into a brain, and which becomes surrounded and pro- tected by a cartilaginous capsule or skull. VERTUE, GEORGE, an English en- graver, born in Westminster, in 1684. He enjoyed the patronage of Sir Godfrey Kneller, and became engraver to the Society of Antiquaries in 1717. His best known works include 12 portraits of poets and 10 portraits of Charles I. and his friends. He died in London, July 24, 1756.
