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 Medusas or of medusiform gonopnores.

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 Anarthropoda.

Vermiform

(Lat. vermis, worm; and 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 organic infusions.

Viperina

(Lat. vipera, 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 cartilage " 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 swordlike tails.

Xylophagous

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