5 8 



GLOSSARY 



proach of danger is thus communicated to 

 other members of the community. 



Simple epithelium, epithelium only one cell 

 thick. 



Sinupalliate (L. simis, a bay), in Bivalve 

 Molluscs, with a posterior indentation in the 

 pallial line, caused by the attachment of a 

 muscle for drawing- back the siphons. 



Siphon (L. sipho, a siphon), in aquatic Mol- 

 luscs, a tubular prolongation of the mantle 

 by which water enters (inhalent siphon) or 

 leaves (exhalent siphon) the gill-chamber. 



Siphuncle (L. siphunculus, a small pipe), in 

 the Pearly Nautilus and many extinct Ce- 

 phalopods, a sort of tube that runs through 

 the chambers of the shell. 



Society, an association of gregarious animals. 



Soma (Gk. for body), the body of an animal 

 exclusive of the germ-cells. 



Somatic variation, variation of the soma 

 (which see). 



Spat, the free-swimming larvae or fry of Oy- 

 sters, Mussels, &c. 



Special creation, applied to the almost obso- 

 lete view that all species or kinds of organism 

 have been independently created. See Evolu- 

 tion. 



Sperm (Gk. sp&rma, seed), a small and usually 

 motile propagative cell, which fertilizes an 

 egg-cell (ovum) by fusing with it. 



Spermaceti, in the Sperm-Whale, liquid fat 

 contained in a deep depression on the upper 

 side of the skull. 



Spermary, an organ producing sperms. 



Spicule, (L. spiculum, a sharp point), in some 

 Zoophytes (Coelenterata), Sponges, and Ani- 

 malcules (Protozoa), an element of the 

 skeleton, of varied shape and chemical com- 

 position. 



Spinal cord, or Spinal marrow, a cylindrical 

 nerve-mass, constituting the hinder part of 

 the central nervous system in a vertebrate 

 animal. 



Spinal nerve, a nerve taking origin in the 

 spinal cord. 



Spinnerets, in Spiders, small rounded projec- 

 tions on the under side of the abdomen, on 

 which the silk glands open. 



Spiracle, (L. splro, I breathe): (i) the external 

 opening of the Spiracular cleft (which see); 

 (2) the blow-hole (nostril) of a whale. 



Spiracular cleft, the front gill-cleft of some 

 Fishes (e.g. Sharks), which is losing or 

 beginning to lose its original function. 

 Spleen (the Greek name), a large abdominal 

 ductless gland in Vertebrates, of doubtful 

 function. It is richly provided with blood- 

 vessels. 



Splenic fever. See Anthrax. 

 Splint-bones, in the Horse, &c,, the dwindled 

 remains of 2nd and 4th metacarpals or meta- 

 tarsals. 



Spore (L. spora, seed), in some Animalcules, 

 one of the minute parts into which the body 



breaks up during vegetative propagation of 

 a particular kind. 



Spore-formation, in some Animalcules, vege- 

 tative propagation by means of spores. 

 Sporocyst (Gk. spora, seed ; cystis, a bladder), 

 in Flukes, a shapeless bag-like stage in the 

 life-history. 



Sporoduct, in some Gregarines, one of the 



tubes by which the spores pass out of the 



firm case (cyst) in which they are produced. 



Sporosac (Gk. sptira, seed), in Zoophytes, a 



degenerate Gonophore (which see). 

 Staggers, in Sheep, a disease due to the 

 presence of tape-worm cysts on the brain. 

 Stamen (Gk. stemon, a thread), a slender 

 modified flower-leaf, which produces pollen. 

 Statoblast (Gk. states, resting; blastbs, a bud), 

 in fresh-water Moss-Polypes, an internally 

 formed winter-bud. 



Sternal: (i) in Vertebrates, relating to the 

 breast-bone or sternum ; (2) in Arthropods, 

 near the sternal or under side of the body. 

 Sternum, pi. -a (Gk. sterntin, the breast or 

 breast-bone): (i) in Vertebrates, the breast- 

 bone; (2) in Arthropods, that part of the 

 exoskeleton covering the ventral surface of 

 a segment. 



Stigma, pi. -ata (Gk. for a mark): (i) the 

 opening of an air-tube in Insects, &c. ; (2) in 

 Plants, the receptive surface to which pollen- 

 grains adhere. 



Stimulus, pi. -i (L. for an ox-goad), any 

 physical or chemical agent by which a sense- 

 organ is thrown iiato activity. 

 Sting, a piercing weapon that inflicts a poi- 

 soned wound. The name is not applied to 

 parts connected with the mouth, such as the 

 poison-fangs of a Viper. 

 Stipes (L. for a branch, or stump), in Insects, 



the second joint of the second jaw. 

 Stratified: (i) of epithelium, more than one 



cell thick; (2) of rocks, arranged in layers. 

 Stratum, pi. -a (L. for pavement), a layer of 



rock. 



Struggle for existence, a metaphorical way 

 of expressing the strenuous nature of Ac- 

 commodation (which see). 

 Sturdy. See Staggers. 

 Subclavius, in Birds, the muscle which raises 



the wing. 

 Sublingual glands, a pair of salivary glands 



situated under the tongue. 



Submaxillary glands, a pair of salivary glands 



situated between the halves of the lower jaw. 



Submentum (L. sub, under; mentum, the chin), 



in Insects, the basal part of the lower lip. 

 Supination (L. supinus, lying on the back), 

 position of forearm when palm of hand is 

 directed upwards. 

 Supra -scapula, a skeletal element present 



above the scapula in some animals. 

 Sur-royal, the fourth branch of a Red Deer's 



antler (counting from its base). 

 Survival of the fittest. See Nattiral selection. 



