Ophiuroidea
an order of the Echinodermata, comprising star fishes known as brittle stars and sand stars. These animals have long slender-jointed arms, which may either be branched or simple. drical and without a bony exoskeleton. pustular, purulent (in the new-born inno Vertebræ procœlous, with rudimentary transverse processes. They have sternum, pectoral arch, forelimbs, or sacrum; nor as a rule are traces of hinder limbs present, though they occasionally occur, e. g., in Python. Hooked conical teeth are always present, anchylosed with the jaw. The order is preeminently tropical, the species rapidly diminishing as the distance from the equator increases, and wholly ceasing before the Arctic or Antarctic Circle is reached. The classification is not fixed.
Acording to Wallace, the order contains 25 families. There is another and natural division into three sub-orders: (1) Thanatophidia (venomous snakes), with two groups, Proteroglyphia and Solenoglyphia; (2) Colubriformes (Innocuous colubriform snakes); and (3) Typhlopidæ (blind snakes).