402 PRINCIPLES OF ANIMAL BIOLOGY 



Sciurinae {si' u ri' nee). The subfamily of Sciuridae comprising the marmots, squirrels, 

 and chipmunks. 



Sciuromorpha (si' u ro mor' fa) . The suborder of rodents comprising the squirrel- 

 like forms. 



Sciurus (siu'rus). The genus including the arboreal squirrels. 



Scolex (sko' leks). The "head" or attaching organ from which are budded off the 

 proglottides of a tapeworm chain. 



Scolopendra {sko' lo pen' dra). A genus of centipedes. 



Scyphozoa (si'fozo'a). A class of Ccelenterata, jellyfishes of large size which have 

 no hydroid form in the life cycle. 



Secondary (sek' und n ri) . For application to spermatocytes see spermatocyte. 

 For application to oocytes, see oocyte. 



Secretin (sekre'tin). A substance produced in the small intestine and serving to 

 stimulate secretion by the pancreas. 



Secretion (se kre' shun). The act of producing from the blood or other fluids or 

 substances in the protoplasm some new material to be used in metabolism. Also 

 the new substance thus formed. 



Sedimentary (sed' i men' ta ri) . Formed from sediment; said of rocks originally 

 deposited under water, and now found in layers. 



Segmentation (seg' men ta' shun). Same as cleavage. 



Segregation (seg' re ga' shun). The separation of the genes of a homologous pair at 

 the time of maturation of the germ cells, or at some other time, so that each germ 

 cell receives only one member of the pair. Sometimes applied also to the inde- 

 pendent distribution of genes of different pairs to the germ cells. 



Self -fertilize (self fer' ti lize). To fertilize the eggs of an individual by sperms of the 

 same individual. 



Semi -circular canal (sem' i ser' ku ler ka naV). One of several curved tubes forming 

 part of the inner division of the ear in vertebrates. 



Seminal receptacle (sem' i nal re sep' ta k'l). An organ in a female animal for the 



reception and storage of spermatozoa from the male. 

 Seminal vesicle (sem' i nal ves'ik'l). One of several bodies closely connected 



with the testes in the earthworm, in which a large part of the development of the 



spermatozoa takes place. Also, an enlargement in the vas deferens or similar duct 



in which sperms may be stored in various animals. 

 Semi-permeable (sem' i per' me a b'l). Permitting the passage of solvents but 



preventing the passage of dissolved substances. 

 Sensory (sen' so ri). Pertaining to sensation; applied to a neuron which transmits an 



impulse resulting in sensation, or by extension to any other receiving neuron 



whether concerned with sensation or not. 

 Sepia (se' pi a). A genus of cuttlefishes (mollusks) from which certain black inks are 



derived. Also the black substance produced by these cuttlefishes. 

 Septum (sep' turn). A partition. 



Sessile (ses' sil) Attached directly, as distinguished from stalked. Sometimes, 



also, attaclied,as distingushed from free-living. 

 Seta (se' ta) (pi., setae, se' tee). A spine; specifically, one of the spines projecting 



from the somites of an earthworm and used for locomotion. 

 Severino, Marco Aurelio (sev' er ee' no). Italian physician, professor in University of 



Naples, 1580-1656. 



