Rotatoria

( = Rotifera).

Rotifera

(Lat. rota, wheel; and fero, I carry). A class of the Scolecida (Annuloida) characterised by a ciliated "trochal disc."

Rugosa

(Lat. rugosus, wrinkled). An order of Corals.

Rumen

(Lat. the throat). The first cavity of the complex stomach of Ruminants ; often called the " paunch."

Ruminantia

(Lat. ruminor, I chew the cud). The group of Hoofed Quadrupeds (Ungulata) which "ruminate" or chew the cud.

Sacrum

The vertebrae (usually anchylosed) which unite with the haunch-bones (ilia) to form the pelvis.

Sand-canal

(=Stone-canal). The tube by which water is conveyed from the exterior to the ambulacral system of the Echinodermata.

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 identical with protoplasm.

Sarcoids

(Gr. sarx; and eidos, form). The separate amoebiform particles which in the aggregate make up the " flesh " of a Sponge.

Sauria

(Gr. saura, a lizard). Any lizard-like Reptile is often spoken of as a called by Huxley Plesiosauria, from the typical genus Plesiosaurus.

SAURURAE

(Gr. saura; oura, tail). The extinct order of Birds comprising only the Archaeopteryx.

Scansores

(Lat. scando, I climb). The order of the Climbing Birds (Parrots, Woodpeckers, &c).

Scaphognathite

(Gr. skaphos, boat; and gnathos, jaw). The boat-shaped appendage (epipodite) of the second pair of maxillae in the Lobster, the function of which is to spoon out the water from the branchial chamber.

Scapula

(Lat. for shoulder-blade). The shoulder-blade of the pectoral arch of Vertebrates ; in a restricted sense, the row of plates in the cup of Crinoids, which give origin to the arms, and are usually called the " axillary radials."

Sclerenchyma

(Gr. skleros, hard; and enchuma, tissue). The calcareous tissue of which a coral is composed.

Sclerites

(Gr. skleros). The calcareous spicules which are scattered in the soft tissues of certain Actinozoa.

Sclerobasic

(Gr. skleros, hard ; basis, pedestal). Applied to the coral which is produced by the coenosarc in certain Actinozoa (e.g., Red Coral), and which forms a solid axis which is invested by the soft parts of the animal.

"Saurian ;" but the term is sometimes restricted to the Crocodiles alone, or to the Crocodiles and Lacertilians.

Saurobatrachia

(Gr. saura; batrachos, frog). Sometimes applied to the order of the tailed Amphibians (Urodela).

Sauropsida

(Gr. saura ; and opsis, appearance). The name given by Huxley to the two classes of the Birds and Reptiles collectively.

Sauropterygia

(Gr. saura; pterux, wing). An extinct order of Reptiles.

It is called "foot-secretion" by Mr Dana.