406 PRINCIPLES OF ANIMAL BIOLOGY 



Stylonychia {sti' lo nik' i a). A genus of ciliated Protozoa. 



Sub-epithelial cells (sub' ep i the' H a.l) . In Hydra, rounded cells lodged among the 

 epithelial cells, often near the base of the latter. 



Sub -umbrella {sub' um breV la). The concave side of a medusa. 



Succus entericus {suk' kus en ter' i kus). The fluid secreted by the small 

 intestine. 



Sucker {suk' er). An attaching organ beneath the head of a frog tadpole; a similar 



organ on the "head" or scolex of a tapeworm colony; also the attaching organ 



of leeches. 

 Suctoria {siik to' ri a). A subclass of Infusoria which bear no cilia when adult, but 



have tube-like tentacles. 

 Sustentative {sus ten' ta tiv) . Supporting; applied to connective tissue and other 



supporting tissues. 

 Suture {su' ture). The line of junction between a septum of a cephalopod shell and 



the outer wall of the shell. Also the immovable joint between two flattened bones, 



as those of the skull. 

 Swammerdam, Jan {swahni' mer dahm), Dutch naturalist, anatomist and entomolo- 

 gist, 1637-1680. 

 Swimmeret {swim' mer et). One of a number of branched appendages beneath the ab- 

 domen of a crayfish. 

 Syllis ramosa {siV lis ra mo' so). A species of marine anneUd worm which produces 



colonies by budding. 

 Symbiosis {sim' bi o' sis). The association of two species of animal for their mutual 



benefit. 

 Symbiote {sim'biote). An animal which lives in a symbiotic relationship with 



another species; called also symbiont. 

 Symbiotic {sim' bi of ik) . Of the nature of symbiosis. 

 Symmetrical {sim met' ri kal). Of a form that may be divided by a line or plane into 



two parts which are mirrored images of each other. 

 Symmetry {sim' me tri) . The state of being symmetrical. 

 Sympathetic nervous system (sim' pathet'ik). Two longitudinal nerve cords and 



associated ganglia in the dorsal region of vertebrates. 

 Sympheidole {sim' fi do' le). A genus of ants. 

 Synapse {sin' aps). The point of contact of two neurons. 

 Synapsis {sin ap' sis). The pairing of maternal with paternal chromosomes early 



in the maturation of the germ cells. 

 Syncytium {sin sish' i um). An undivided mass of protoplasm containing several or 



many nuclei. 

 Synura {si nu' ra). A genus of free-swimming colonial flagellate Protozoa, some 



species of which cause disagreeable odors or tastes in drinking water. 

 Syrphid {ser' fid). A fly of the family Syrphidae. 

 System {sis' tem) . A collection of organs concerned with the same general function, as 



digestion. 

 Systematic zoology {sis' tem at' ik). See taxonomy. 

 Systemic circulation {sis tem' ik ser' ku Ui' shun). The circulation of the blood 



through the body in general, as distinguished from that through the lungs or lungs 



and skin (pulmonary or pulmocutaneous). 



