Glossary. 
377 
Terebratula (Lat. terebratus , bored or pierced). A genus 
of Brachiopoda, so called in allusion to the perforated 
beak of the ventral valve. 
Thylacoleo (Gr. thulakos , a pouch ; leon , a lion). An ex- 
tinct genus of marsupials. 
Trachyte (Gr trachus , rough). All igneous rock, break- 
ing with a rough surface, and composed chiefly of 
glassy felspar. 
Travertine. A rock composed of carbonate of lime precipi- 
tated from water, practically indentical with tufa. 
Trigonia (Gr. treis, three ; gonia , angle). A genus of 
bivalve molluscs. 
Trilobita (Gr. treis, three ; lob os, a lobe). An extinct 
order of Crustaceans. 
Tuff. A term used in this work to indicate the less coarse 
and more distinctly bedded kinds of volcanic ash. 
Tufa. A precipitate of carbonate of lime from water. 
Univalve (Lat. anus , one ; valvce , folding-doors). A shell 
composed of a single piece or valve. 
Ventral (Lat. venter , the stomach). Relating to the in- 
ferior surface of the body. 
Vertebra (Lat. vertebra , a bone of the back, from veter e , 
to turn.) One of the bony segments of the vertebral 
column or backbone. 
Yertebraria. A peculiar genus of fossil plants hitherto 
known with certainty only from India and Australia. 
Probably roots of Glossopteris. Common in the 
Permo-Carboniferous beds, "Newcastle. 
Yertebrata. The division of the animal kingdom roughly 
characterised by the possession of a backbone. 
