#Ros' trum#, a beak-like projection or snout.

#Ru' mi nant#, chewing the cud.

#Sac#, a cavity or pouch.

#Sa' crum#, a composite bone formed by the union of vertebrae in the region of hips.

#Scap' u la#, the shoulder-blade.

#Sep' tum# (pl. #sep' ta#), a wall or part.i.tion between two cavities.

#Se' ta# (pl. #se' tae#), small bristles or stiff hairs.

#s.e.x' u al#, pertaining to s.e.x.

#Si' nus ve no' sus#, an enlargement of the termination of the large veins.

#Si' phon#, a tube-like organ.

#So' mites#, the serial segments or rings composing the bodies of many animals.

#Spe' ci es#, a word used in cla.s.sification to designate a group of animals differing only in minor details.

#Sper' ma ry#, the organ in which sperm cells are developed.

#Sperm cells#, the small, often motile, reproductive cell, which fuses with the egg cell.

#Spic' ules#, tiny needles of mineral substance found in the walls of many animals, notably sponges.

#Spi' ra cle#, an opening into the tracheal breathing organs of insects.

#Spire#, the coiled portion of a gasteropod sh.e.l.l.

#Spore#, a cell capable of developing into a new organism.

#Sternum#, a bone extending along the lower middle line of the chest region.

#Stom' ach#, the region of the alimentary ca.n.a.l especially adapted to digest food.

#Stom' ach-in tes' tine#, a region of the alimentary ca.n.a.l adapted to both digest and absorb food.

#Sub cla' vi an#, situated beneath the clavicle.

#Su' ture#, the junction of two contiguous structures.

#Swim' mer ets#, the abdominal appendages in crustaceans.

#Sym bi o' sis#, an a.s.sociation of two animals which is mutually helpful.

#Tar' sal#, one of the bones of the tarsus or ankle.

#Tar' sus#, (1) the ankle; (2) the fifth or terminal joint in an insect's leg.

#Ten' ta cles#, special organs for touch; also used sometimes for other purposes.

#Terrifying att.i.tudes#, protective att.i.tudes a.s.sumed by some animals.

#Tho' rax#, the region of the body between the head and abdomen.

#Tib' i a#, (1) the shin-bone; (2) the fourth joint of an insect's leg.

#Tooth#, (1) an organ used in mastication; (2) a tooth-like projection.

#Tra' che a#, a tube which carries air either to the respiratory organ or to the tissues.

#Trunk#, the portion of the body between head and tail.

#Tu' ber cle#, a k.n.o.b-like projection.

#Ul' na#, that bone of the forearm which is on the same side as the little finger.

#Um' bo# (pl. #umbones#), an elevation near the anterior end of a bivalve sh.e.l.l.

#Un' gu lates#, hoofed mammals.

#U re' ter#, a duct connecting the kidney with the urinary bladder.

#U' ro style#, a long bone forming the hinder extremity of the vertebral column of tailless amphibia.

#Vac' u oles#, small, clear spots in cells, filled with a watery fluid. _See_ Food-vacuoles _and_ Contracting vacuoles.

#Valve#, (1) a membranous fold which allows the blood, or other fluids, to flow in only one direction; (2) one of the two parts of the sh.e.l.l of a bivalve.

#Vein#, (1) a blood-vessel carrying blood toward the heart; (2) one of the tubular thickenings of an insect's wing.

#Ve' na ca' va#, a large vein emptying into the right auricle of the heart.

#Ven' tral#, situated on the under surface.

#Ven' tri cle#, any cavity of a hollow organ, as of the brain or heart.

#Ver' mes#, the worms, a poorly defined group of animals, showing bilateral symmetry but without segmented appendages.

#Ver' te bra#, one of the bones of the spinal column.