414 GLOSSARY. 



TELSON (Gr. a limit). The last joint in the abdomen of Crus- 

 tacea; variously regarded as a segment without appendages, or 

 as an azygous appendage. 



TENTACULITES (Lat. tentaculum, a feeler). A genus of Ptero- 

 poda. 



TERERBRATULA (Lat. terebratus, bored or pierced.) A genus of 

 Brachiopoda, so called in allusion to the perforated beak of 

 the ventral valve. 



TEST (Lat. testa, shell.) The shell of Mollusca, which are for 

 this reason sometimes called " Testacea," also, the calcareous 

 case of Echinoderms; also, the thick leathery outer tunic in 

 the Tunic at a. 



TESTACEOUS. Provided with a shell or hard covering. 



TESTUDINJD^E (Lat tesiudo, a tortoise). The family of the Tor- 

 toises. 



TETRABRANCHIATA (Gr. tetra, four; bragchia, gill). The order 

 of Cephalopoda characterized by the possession of four gills. 



TEXULARIA (Lat. texilis, woven). A genus of Foraminifera. 



THECA (Gr. the'ke, a sheath). A genus of Pteropods. 



THECODONTOSAURUS (Gr. theke, a sheath; odous, tooth; saura, 

 lizard). A genus of " Thecodont " Reptiles, so named in allu- 

 sion to the fact that the teeth are sunk in distinct sockets. 



THERIODONT (Gr. tlrtrion, a beast; odous, tooth). A group _of 

 Reptiles so named by Owen in allusion to the Mammalian 

 character of their teeth. 



THORAX (Gr. a breastplate). The region of the chest. 



THYLACOLEO (Gr. thulakos, a pouch; leo, a lion). An extinct 

 genus of Marsupials. 



TRIGONIA (Gr. treis, three; gonia, angle.) A genus of Bivalve 

 Molluscs. 



TRIGONOCARPON (Gr. treis, three; gonia, angle; karpos, fruit). 

 A genus founded on fossil fruits of a three-angled form. 



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

 Crustaceans. 



TRINUCLEUS (Lat. iris, 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. turns, a tower). A genus of the Ammoni- 

 tida. 



U 



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

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



