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An extensive group of Invertebrata, including the Mollusca, Brachiopoda, and Bryozoa. Called also Malacozoaria.

The highest class of Vertebrata. The young are nourished for a time by milk, or an analogous fluid, secreted by the mammary glands of the mother.

(Zoöl.), a breed of domestic cats having a rudimentary tail, containing only about three vertebrae. -- Manx shearwater (Zoöl.), an oceanic bird (Puffinus anglorum, or P. puffinus), called also Manx petrel, Manx puffin. It was formerly abundant in the Isle of Man.

A class of Vertebrata, lower than fishes, characterized by their purselike gill cavities, cartilaginous skeletons, absence of limbs, and a suckerlike mouth destitute of jaws. It includes the lampreys and hagfishes. See Cyclostoma, and Lamprey. Called also Marsipobranchiata, and Marsipobranchii.

illed with spongy pith; pithy. Medullary groove (Anat.), a groove, in the epiblast of the vertebrate blastoderm, the edges of which unite, making a tube (the medullary canal) from which the brain and spinal cord are developed. -- Medullary rays (Bot.), the rays of cellular tissue seen in a transverse section of exogen…

An interarticular synovial cartilage or membrane; esp., one of the intervertebral synovial disks in some parts of the vertebral column of birds. Converging meniscus, Diverging meniscus. See Lens.

One of the serial segments, or metameres, of which the bodies of vertebrate and articulate animals are composed.

The middle body layer in some invertebrates.

The middle one of the three pairs of embryonic renal organs developed in most vertebrates; the Wolffian body.

arts in animals and plants; one of a series of similar parts that follow one another in a vertebrate or articulate animal, as in an earthworm; a segment; a somite. See Illust. of Loeven's larva.

The most posterior of the three pairs of embryonic renal organs developed in many vertebrates.

A division of Invertebrata which includes the classes Brachiopoda and Bryozoa; -- called also Anthoid Mollusca.

A group of vertebrates, including the birds and reptiles, or those that have only one occipital condyle; the Sauropsida.

Same as Vertebrata.

The Vertebrata.

found associated with hemoglobin in the muscle tissue of a large number of animals, both vertebrate and invertebrate.

e specialized coördinating apparatus which endows animals with sensation and volition. In vertebrates it is often divided into three systems: the central, brain and spinal cord; the peripheral, cranial and spinal nerves; and the sympathetic. See Brain, Nerve, Spinal cord, under Spinal, and Sympathetic system, under Sym…

on the side with, the neural, or cerebro-spinal, axis; -- opposed to hemal. As applied to vertebrates, neural is the same as dorsal; as applied to invertebrates it is usually the same as ventral. Cf. Hemal. Neural arch (Anat.), the cartilaginous or bony arch on the dorsal side of the centrum of the vertebra in a segmen…

to both the neuron and the enteron; as, the neurenteric canal, which, in embroys of many vertebrates, connects the medullary tube and the primitive intestine. See Illust. of Ectoderm.

Between the neural arch and the centrum of a vertebra; as, the neurocentral suture. Huxley.