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The closing subdivision of the Devonian age in America. The rocks of this period are well developed in the Catskill mountains, and extend south and west under the Carboniferous formation. See the Diagram under Geology.

her vegetable or animal, is a cell; the whole series of cells having been formed from the development of the germ cell and by differentiation converted into tissues and organs which, both in plants ans animals, are to be considered as a mass of minute cells communicating with each other. -- Cellular tissue. (a) (Anat.…

also to designate a modified mass of protoplasm about a centrosome whether aster rays are developed or not.

Mollusca, including all except the bivalves; -- so called because the head is distinctly developed. See Illustration in Appendix.

Form or development of the skull; as, the races of man differ greatly in cephalism.

sical structure; localization of important organs or parts in or near the head, in animal development. Dana.

tly two living species have been discovered in Australian rivers. They have lungs so well developed that they can leave the water and breathe in air. In Australia they are called salmon and baramunda. See Dipnoi, and Archipterygium.

vonian system in America, so named from the Chemung River, along which the rocks are well developed. It includes the Portage and Chemung groups or epochs. See the Diagram under Geology.

A scientific study of children, undertaken for the purpose of discovering the laws of development of the body and the mind from birth to manhood.

ipeds. They have a single pair of elongated legs attached laterally to each segment; well developed jaws; and a pair of thoracic legs converted into poison fangs. They are insectivorous, very active, and some species grow to the length of a foot.

A plastid containing chlorophyll, developed only in cells exposed to the light. Chloroplasts are minute flattened granules, usually occurring in great numbers in the cytoplasm near the cell wall, and consist of a colorless ground substance saturated with chlorophyll pigments. Under light of varying intensity they exhib…

The development of cartilage.

the fetus in the womb; also, the similar membrane investing many ova at certain stages of development.

changes of color in the translucent skin of such animals as possess them. They are highly developed and numerous in the cephalopods.

An embryonic cell which develops into a pigment cell.

photographic picture taken upon paper prepared by the use of a sensitive salt of iron and developed by the application of chloride of gold. Abney.

The germinating point in the embryo of a seed; the point in the yolk of an egg at which development begins.

An epoch at the close of the American lower Silurian system. The rocks are well developed near Cincinnati, Ohio. The group includes the Hudson River and Lorraine shales of New york.

A division of passerine birds in which the vocal muscles are but little developed, so that they lack the power of singing.

One of a pair of male copulatory organs, developed on the anterior side of the ventral fins of sharks and other elasmobranchs. See Illust. of Chimæra.