Somite

(Gr. soma). A single segment in the body of an Articulate animal.

Spermarium

The organ in which spermatozoa are produced.

Spermatophores

(Gr. sperma, seed; phero, I carry). The cylindrical capsules of the Cephalopoda, which carry the spermatozoa ; sometimes called the "moving filaments of Needhara."

Spermatozoa

(Gr. sperma, seed; and zoon, animal). The microscopic filaments which form the essential generative element of the male.

Sphaeridia

(Gr. sphairidion, a little ball or sphere). Minute stalked appendages with button-shaped heads carried by most living Sea-urchins, and supposed to be organs of sense.

Spicula

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

Spinnerets

The organs by means of which Spiders and Caterpillars spin threads.

Spiracles

(Lat. spiro, I breathe). The breathing-pores, or apertures of the breathing-tubes (tracheae) of Insects. Also the single nostril of the Hag-fishes, the "blow-hole " of Cetaceans, etc.

Splanchnoskeleton

(Gr. splagchna, viscera ; skeletos, dry). The hard structures occasionally developed in connection with the internal organs or viscera.

Sponge-particles

(See Sarcoids.)

Spongida

(Gr. spoggos, a sponge). The division of Protozoa commonly known as sponges.

Spores

(Gr. spora, seed). Germs, usually of plants ; in a restricted sense, the reproductive "gemmules" of certain sponges.

Sporosacs

(Gr. spora, seed; and sakkos, a bag). The simple generative buds of certain Hydrozoa, in which the medusoid structure is not developed.

Squamata

(Lat. squama, a scale). The division of reptiles comprising the Ophidia and Lacertilia in which the integument develops horny scales, but there are no dermal ossifications.

Statoblasts

(Gr. statos, stationary ; blastos, bud). Certain reproductive buds developed in the interior of Polyzoa, but not liberated until the death of the parent organism.

Steganophthalmata

(Gr. steganos, covered ; and ophthalmos, the eye). Applied by Edward Forbes to certain Medusae, in which the sense-organs ("marginal bodies") are protected by a sort of hood. The Steganophthalmata are now separated from the true Medusidae, and placed in a separate division under the name Lucernarida.

Stellerida

(Lat. stella, star). Sometimes employed to designate the order of the Star-fishes.

Stelliform

Star-shaped.

Stemmata

(Gr. stemma, garland). The simple eyes, or "ocelli," of certain animals, such as Insects, Spiders, and Crustacea.

Sternum

(Gr. sternon). The breast-bone.

Stigmata

The breathing-pores in Insects and Arachnida.

Stolon

(Gr. stolos, a sending forth). Offshoots. - The connecting processes of sarcode in Foraminifera; the connecting tube in the social Ascidians ; the processes sent out by the coenosarc of certain Actinozoa.