476 OLOSSART. 



TuBULIBnA^X'I^A'TA, an order of mollusks, to which the Vcrme- 

 tus belongs. The gills in some of the species are arranged 

 ill a somewhat tubular form, and follow all the windings of 

 the convoluted shell. 



Tunica'ta, a class of molluscous animals, having a leathery 

 or a membranous covering, instead of one formed of shelly 

 matter. In many other respects their structure is very re- 

 markable and peculiar. Lat. tunica, a tunic. 



Typical, that w-hich is regarded as the type or representative 

 of a particular group. 



Undulation, a movement in cui-ved or arching lines resembling 

 that of a wave. Lat. undulatus, from unda, a ■wave. 



Unique, singular, single, one only. French, unique. 



Univalve, a terra applied to a shell which, like that of the 

 whelk or the limpet, consists of only one piece. 



Vacuum, a space unoccupied by matter — most usually employed 

 to denote a space from which the air has been exhausted. 



Ventral, belonging to the belly. Lat. venter, ventris, the belly. 



Ventricle, a term applied to one or to two of the cavities in 

 the heart of the vertebrate animals. 



Vermiform, worm-shaped. Lat. vermis, a worm. 



Vermigrade, moving like a worm. Lat. vermis, a worm, and 

 gradior, I advance. 



Vertebral Column. — " Vertebral, as consisting of segments of 

 the skeleton which turn one upon the other, and as being 

 the centre on which the whole body can bend and rotate; 

 from the Latin, verto, vertcre, to turn." — Owen, 



Vesicle, a small enclosed space like a little bladder. Lat 

 vesicula. 



ViBRATiLE, possessing the power to vibrate. Lat. vibrare, to 

 shake. 



Vitalised, with the power of sustaining life. The term is ap- 

 plied to water containing atmospheric air, and which is 

 thereby fitted for the respiration of aquatic animals. Lat. 

 vita, iiie. 



Vivified, endued with life. Lat. vivere, to live — vivificare, to 

 cause or give life. 



Vivi'PAROUS, producing the young alive. The word is used in 

 opposition to oviparous, already mentioned. 



^Vealden Formation, a geological term applied to a fresh- 

 water deposit in the South of England. It belongs to the 

 upper part of the secondary series of rocks, and attests the 

 former existence in that region of a large river. 



Zoology, that department of science that treats of the struc- 

 ture, habits, and classification of animals. Gr. zoon, an 

 animal, and logos, a discourse. 



Zoologist, one who has acquired a knowledge of Zoology. 



Zoophytes, a class of radiated animals, formerly supposed to 

 partake of the nature of both animals p,nd plants. Gr. zoon 

 an animal, and phyton, a plant. 



THE END. 



