203 Sim 



Shank. — The tibia (Dan. shank. Swed. shank, a 

 bone of tbe leg. Der. skink.) See Tibia. 



Sheath. — An organ generally pertaining uO the 

 instrumenta suctoria. (A.S. sceath.) 



Shellac. — A secretion formed by insects (coccidae) 

 which is of a glutinous nature. Valuable in 

 the manufacture of hats. Used for varnishes, 

 sealing wax, lacquer work, etc. (A.S. scell, and 

 Pers. lac. 



Sigma. — The name of the Greek letter 2, a, ?, 

 equal to the English S. 



Sigmoidal. — S-shaped, curved like the Greek sigma. 

 Lanceolate and concave on one side at the base, 

 and on the other side at the apex. (Gr. sigma, 

 and eidos, like.) 



Signatures. — Markings (of colour chiefly) upon a 

 surface, resembling in some degree letters and 

 characters. (L. signatura, from signo, to mark, 

 sign, etc.) 



Signate. — Marked with signatures. — (L. signo.) 



Simple. — (Antennae.) The term used when a 

 capitate antennae is so formed by one joint only, 

 [See Compound in contra-distinction.] (L. 

 simplex, one fold, from semel, once, and plico 

 to fold.) 



Simple (simplex). — With no unusual addition or 

 modification. 



Simple ocellus.— When the e//e of colour consists 

 only of an iris and pupil. (L. simplex and 

 ocellus.) 



