8l8 GLOSSARY. 



UNILOCULAR (Lat. unus, one ; and loculus, a little purse). Possessing a single 

 cavity or chamber. Applied to the shells of Foraminifera and Mollusca. 



UNIVALVE (Lat. unus, one; valvce, folding doors). A shell composed of a 

 single piece or valve. 



UEODELA (Gr. oura, tail ; delos, visible). The order of the tailed Amphibians 

 (Newts, &c.) 



URTICATING CELLS (Lat. urtica, a nettle). (See Cnidse). 



VACUOLES (Lat. vacuics, empty). The little cavities formed in the interior of 

 many of the Protozoa by the presence of little particles of food, usually sur- 

 rounded by a little water. These are properly called "food vacuoles," and 

 were supposed to be stomachs by Ehrenberg. Also the clear spaces which 

 are often seen in the tissues of many Ccelenterata. 



VARICES (Lat. varix, a dilated vein). The ridges or spinose lines which mark 

 the former position of the mouth in certain univalve shells. 



VASCULAR (Lat. vas, a vessel). Connected with the circulatory system. 



VELIGER (Lat. velum, a sail ; gero, I carry). A name applied to the larvae of 

 most of the Molluscs, on account of their possessing ciliated lappets forming 

 a "velum." 



VELUM (Lat. a sail). The membrane which surrounds and partially closes the 

 mouth of the "disc " of Medusce or of medusiform gonophores. 



VENTRAL (Lat. venter, the stomach). Relating to the inferior surface of the 

 body. 



VENTRICLE (Lat. dim. of venter, stomach). Applied to one of the cavities of 

 the heart, which receives blood from the auricle. 



VERMES (Lat. vermes, a worm). Sometimes employed at the present day in 

 the same, or very nearly the same, sense as Annuloida, or as Annuloida plus 

 the A narthropoda, 



VERMIFORM (Lat. vermis, worm ; &&& forma, form). Worm-like. 



VERTEBRA (Lat. verto, I turn). One of the bony segments of the vertebral 

 column or backbone. 



VERTEBRATA (Lat. vertebra, a bone of the back, from vertere. to turn). The 

 division of the Animal Kingdom roughly characterised by the possession of 

 a backbone. 



VESICLE (Lat. vesica, a bladder). A little sac or cyst. 



VIBRACULA (Lat. vibro, I shake). Long filamentous appendages found in many 

 Polyzoa. 



VIBRIONES (Lat. vibro, I shake). The little moving filaments developed in or- 

 ganic infusions. 



VIPERINA (Lat. vipara, a viper). A group of the Snakes. 



VITREOUS (Lat. vitrum, glass). Glassy, transparent. The "vitreous" sponges 

 are those with a skeleton of flint. 



VIVIPAROUS (Lat. vivus, alive ; and pario, I bring forth.) Bringing forth 

 young alive. 



WHORL. The spiral turn of a univalve shell. 



XIPHISTERNUM (Gr. xiphos, sword ; sternon, breast-bone). The inferior or 

 posterior segment of the sternum, corresponding with the ' ' xiphoid carti- 

 lage " of human anatomy. 



XiPHOSURA (Gr. xiphos, a sword ; and oura, tail). An order of Crustacea, 

 comprising the Limuli or King-Crabs, characterised by their long sword- 

 like tailrf. 



XYLOPHAGOUS (Gr. xulon, wood ; and phago, I eat). Eating wood, applied to 

 certain Mollusca. 



ZEUGLODONTID^J (Gr. zeugU, a yoke ; odous, a tooth). An extinct family of 

 Cetaceans, in which the molar teeth are two-fanged, and look as if composed 

 of two parts united by a neck. 



ZOCECIUM (Gr. zoon, animal ; oikos, house). The " cell " or chamber in which 

 the polypide of a Polyzob'n is contained. 



