QUADRUMANA (Lat. _quatuor_, four; _ma.n.u.s_, hand). The order of Mammals comprising the Apes, Monkeys, Baboons, Lemurs, &c.

RADIATA (Lat. _radius_, a ray). Formerly applied to a large number of animals which are now placed in separate sub-kingdoms (e.g., the _Coelenterata_, the _Echinodermata_, the _Infusoria_, &c.)

RADIOLARIA (Lat. _radius_, a ray). A division of _Protozoa_.

RAMUS (Lat. a branch). Applied to each half or branch of the lower jaw, or mandible, of Vertebrates.

RAPTORES (Lat. _rapto_, I plunder). The order of the Birds of Prey.

RASORES (Lat. _rado_, I scratch). The order of the Scratching Birds (Fowls. Pigeons, &c.)

RECEPTACULITES (Lat. _receptaculum_, a storehouse). An extinct genus of Protozoa.

REPTILIA (Lat. _repto_, I crawl). The cla.s.s of the _Vertebrata_ comprising the Tortoises, Snakes, Lizards, Crocodiles, &c.

RETEPORA (Lat. _rete_, a net; _porus_, a pore). A genus of Lace-corals (_Polyzoa_).

RHAMPHORHYNCHUS (Gr. _rhamphos_, beak; _rhugchos_, nose). A genus of Pterosaurian Reptiles.

RHINOCEROS (Gr. _rhis_, the nose; _keras_, horn). A genus of Hoofed Quadrupeds.

RHIZOPODA (Gr. _rhiza_, a root; and _pous_, foot). The division of _Protozoa_ comprising all those which are capable of emitting pseudopodia.

RHYNCHOLITES (Gr. _rhugchos_, beak; and _lithos_, stone). Beak-shaped fossils consisting of the mandibles of _Cephalopoda_.

RHYNCHONELLA (Gr. _rhugchos_, nose or beak). A genus of Brachiopods.

RODENTIA (Lat. _rodo_, I gnaw). An order of the Mammals; often called _Glires_ (Lat. _glis_, a dormouse).

ROTALIA (Lat. _rota_, a wheel). A genus of _Foraminifera_.

RUGOSA (Lat. _rugosus_, wrinkled). An order of Corals.

RUMINANTIA (Lat. _ruminor_, I chew the cud). The group of Hoofed Quadrupeds (_Ungulata_) which "ruminate" or chew the cud.

SARCODE (Gr. _sarx_, flesh; _eidos_, form). The jelly-like substance of which the bodies of the _Protozoa_ are composed. It is an alb.u.minous body containing oil-granules, and is sometimes called "animal protoplasm."

SAURIA (Gr. _saura_, a lizard). Any lizard-like Reptile is often spoken of as a "Saurian;" but the term is sometimes restricted to the Crocodiles alone, or to the Crocodiles and Lacertilians.

SAUROPTERYGIA (Gr. _sauro_; _pterux_, wing). An extinct order of Reptiles, called by Huxley _Plesiosauria_, from the typical genus _Plesiosaurus_.

SAURURae (Gr. _saura_; _oura_, tail). The extinct order of Birds comprising only the _Archoeopteryx_.

SCANSORES (Lat. _scando_, I climb). The order of the Climbing Birds (Parrots, Woodp.e.c.k.e.rs, &c.)

SCAPHITES (Lat. _scapha_, a boat). A genus of the _Ammonitidoe_.

SCOLITHUS (Gr. _skolex_, a worm; _lithos_, a stone). The vertical burrows of sea-worms in rocks.

SCUTA (Lat. _scutum_, a shield). Applied to any shield-like plates; especially to those which are developed in the integument of many Reptiles.

SELACHIA or SELACHII (Gr. _selachos_, a cartilaginous fish, probably a shark). The sub-order of _Elasmobranchii_ comprising the Sharks and Dog-fishes.

SEPIOSTAIRE. The internal sh.e.l.l of the Sepia, commonly known as the "cuttle-bone."

SEPTA. Part.i.tions.

SERPENTIFORM. Resembling a serpent in shape.

SERTULARIDA (Lat. _sertum_, a wreath). An order of _Hydrozoa_.

SESSILE (Lat. _sedo_, I sit). Not supported upon a stalk or peduncle; attached by a base.

SETHae (Lat. bristles). Bristles or long stiff hairs.

SIGILLARIOIDS (Lat. _sigilla_, little images). A group of extinct plants of which _Sigillaria_ is the type, so called from the seal-like markings on the bark.

SILICEOUS (Lat. _silex_, flint). Composed of flint.

SINISTRAL (Lat. _sinistra_, the left hand). Left-handed; applied to the direction of the spiral in certain sh.e.l.ls, which are said to be "reversed."

SIPHON (Gr. a tube). Applied to the respiratory tubes in the _Mollusca_; also to other tubes of different functions.

SIPHONIA (Gr. _siphon_, a tube). A genus of fossil Sponges.

SIPHONOSTOMATA (Gr. _siphon_; and _stoma_, mouth). The division of _Gasteropodous Molluscs_ in which the aperture of the sh.e.l.l is not "entire," but possesses a notch or tube for the emission of the respiratory siphon.

SIPHUNCLE (Lat. _siphunculus_, a little tube). The tube which connects together the various chambers of the sh.e.l.l of certain _Cephalopoda_ (_e.g._, the Pearly Nautilus).

SIRENIA (Gr. _seiren_. a mermaid). The order of _Mammalia_ comprising the Dugongs and Manatees.

SIVATHERIUM (_Siva_, a Hindoo deity; Gr. _therion_, beast). An extinct genus of Hoofed Quadrupeds.

SOLIDUNGULA (Lat. _solidus_, solid; _ungula_, a hoof). The group of Hoofed Quadrupeds comprising the Horse, a.s.s, and Zebra, in which each foot has only a single solid hoof. Often called _Solipedia_.

SPHENOPTERIS (Gr. _sphen_, a wedge; _pteris_, a fern). An extinct genus of ferns.

SPICULA (Lat. _spicidum_, a point). Pointed needle-shaped bodies.

SPIRIFERA (Lat. _spira_, a spire or coil; _fero_, I carry). An extinct genus of Brachiopods, with large spiral supports for the "arms."

SPIRORBIS (Lat. _spira_, a spire; _orbis_, a circle). A genus of tube-inhabiting Annelides, in which the sh.e.l.ly tube is coiled into a spiral disc.

SPONGIDA (Gr. _spoggos_, a sponge). The division of _Protozoa_ commonly known as sponges.