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

REPTILIA (Lat. repto, I crawl).  The class 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 albuminous 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, Woodpeckers, &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 shell of the Sepia, commonly known as the “cuttle-bone.”

SEPTA.  Partitions.

SERPENTIFORM.  Resembling a serpent in shape.