TRILOBITA (Gr. treis, three; lobos, a lobe).  An extinct order of Crustaceans.

TRINUCLEUS (Lat. tris, three; nucleus, a kernel).  A genus of Trilobites.

TROGONTHERIUM (Gr. trogo, I gnaw; therion, beast).  An extinct genus of Beavers.

TUBICOLA (Lat. tuba, a tube; and colo, I inhabit).  The order of Annelida which construct a tubular case in which they protect themselves.

TUBICOLOUS.  Inhabiting a tube.

TUNICATA (Lat. tunica, a cloak).  A class of Molluscoida which are enveloped in a tough leathery case or “test.”

TURBINATED (Lat. turbo, a top).  Top-shaped; conical with a round base.

TURRILITES (Lat, turris, a tower).  A genus of the Ammonitidoe.

UMBO (Lat. the boss of a shield).  The beak of a bivalve shell.

UNGUICULATE (Lat. unguis, nail).  Furnished with claws.

UNGULATA (Lat. ungula, hoof).  The order of Mammals comprising the Hoofed Quadrupeds.

UNGULATE.  Furnished with expanded nails constituting hoofs.

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; valvoe, folding-doors).  A shell composed of a single piece or valve.

URODELA (Gr. oura, tail; delos, visible).  The order of the Tailed Amphibians (Newts, &c.)

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

VENTRICULITES (Lat. ventriculum, a little stomach).  A genus of siliceous Sponges.

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.

WHORL.  The spiral turn of a univalve shell.

XIPHOSURA (Gr. xiphos, a sworn; and oura, tail).  An order of Crustacea, comprising the Limuli or King-Crabs, characterised by their long sword-like tails.

XYLOBIUS (Gr. xulon, wood; bios, life).  An extinct genus of Myriapods, named in allusion to the fact that the animal lived on decaying wood.

ZAPHRENTIS (proper name).  A genus of Rugose Corals.

ZEUGLODONTIDAE. (Gr. zeugle, 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.

ZOOPHYTE (Gr. zooen, animal; phuton, plant).  Loosely applied to many plant-like animals, such as Sponges, Corals, Sea-anemones, Sea-mats, &c.