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simulation (sim'ula'shun) . [L. 

 simulare, to simulate.] The as- 

 sumption by some animals of 

 features or structures intended to 

 deceive enemies and so protect 

 themselves, as the forms of leaf 

 and stick Insects, and all the 

 varieties of protective coloration 

 (zool.}. 



sincipital (sinsip'ital) a. [L. semi, 

 half; caput, head.] Pert, the 

 sinciput (anat}. 



sinciput (sin'siput) n. [L. semi, half ; 

 caput, head.] The upper or fore 

 part of the head (anat.}. 



sinistral (sin'istral) a. [L. sinister, 

 left.] On the left ; appl. a shell 

 whose spiral turns in the opposite 

 direction to dextral (zool.}. 



sinistrorse (sin'istrors) a. [L. sinister, 

 left ; vertere, to turn.] Appl. a 

 spiral twining towards the left ; 

 opp. dextrorse (dot.}. 



sinuate' (sln'uat)'a. [L. sinus, curve.] 

 Winding ; tortuous ; having a wavy 

 indented margin, as leaves (bot.}. 



sinuous, sinuate. 



sinupalliate (sin'upal'iat) a. [L. sinus, 

 curve ; pallium, mantle.] In Mol- 

 luscs, having a well - developed 

 siphon, and so an indented pallial 

 line ; opp. integripalliate (zool.}. 



sinus (sl'nus) n. [L. sinus, curve.] 

 A cavity, depression, or dilation 

 (zool., anat.} ; a groove or indenta- 

 tion (bot.}. 



sinus pocularis, uterus masculinus. 



sinus rhomboidalis, in vertebrate 

 embryos, the posterior incompletely- 

 closed part of the medullary canal 

 (emb.} ; later, a dilation of the canal 

 in the sacral region, formed from 

 it (anat.}. 



sinus venosus, the posterior chamber 

 of the tubular heart of the embryo 

 (emb.} ; in lower vertebrates, a 

 corresponding structure receiving 

 venous blood and opening into the 

 auricle (zool.} ; the cavity of the 

 auricle (anat.). 



sinusoid (sl'nusoid) n. [L. sinus, 

 curve ; Gk. eidos, resemblance.] A 

 minute blood space in organ tissue 

 formed from intercrescence of endo- 

 dermal cells and vascular endo- 

 thelium, especially in the liver, 

 where sinusoids give rise to 



"capillaries" of the hepatic lobules 

 of the adult liver (c/nb.}. 



siphon (si'fon) n. [Gk. siphon, a reed 

 or tube.] A prolongation of the 

 mantle in Lamellibranchs into a 

 longer and shorter tube through 

 which the water of respiration 

 enters and leaves the mantle cavity ; 

 a similar respiratory structure of 

 Gasteropods, found modified also 

 in Cephalopods ; a sucking pro- 

 boscis (zool.}. 



siphonate (sl'fonat) a. [Gk. siphon, 

 tube.] Furnished with a siphon 

 or siphons (zool.}. 



siphonet (sl'fonet) n. [Gk. siphon, 

 tube.] The honeydew tube of an 

 Aphid (zool.}. 



siphonial (slfo'nial) a. [Gk. siphon, 

 tube.] Pert, a siphonium. 



siphonium (slf o'nium) n. [Gk. siphon, 

 tube.] A membranous tube con- 

 necting the air - passages of the 

 quadrate with an air-space in the 

 mandible (Crocodile) (zool.}. 



siphonogamous (sl'fonog'amus) a. 

 [Gk. siphon, tube ; gamos, marriage.] 



. Securing fertilization by a pollen 

 tube (bot.}. 



siphonogamy (sl'fonog'ami) n. [Gk. 

 siphon, tube.] Fertilization by 

 means of a pollen tube (bot.}. 



siphonoglyph (sl'fonoglif) n. [Gk. 

 siphon, tube ; glyphein, to engrave.] 

 One of two longitudinal grooves 

 of the gullet of Sea-anemones 

 (zool.}. 



siphonoplax (sl'fdnoplaks') n. [Gk. 

 siphon, tube ; plax, a tablet.] A 

 calcareous plate connected with 

 the siphon of certain Molluscs 

 (zool.}. 



siphonostele (sffonostel') n. [Gk. 

 siphon, tube ; stele, a post.] The 

 hollow vascular cylinder of a stem, 

 containing pith (bot.}. 



siphonostelic (sl'fonostel'ik) a. [Gk. 

 siphon, tube ; stele, a post.] Appl. 

 hollow cylindrical stems, chiefly 

 of Ferns (bot.}. 



siphonostomatous (sl'fb'nostom'atus) 

 a. [Gk. siphon, tube ; stoma, 

 mouth.] With tubular mouth ; 

 having the front margin of the shell 

 notched for emission of the siphon 

 (zool.}. 



siphonozooid (si'fonozo'oid) n. [Gk. 



