GLOSSARY. Si/ 



THECOSOMATA (Gr. tlieke; and soma, tody). A division of Pteropodous 

 Molluscs, in which the body is protected by an external shell. 



THERIOMORPHA (Gr. ther, beast ; morphe, shape). Applied by Owen to the 

 order of the Tail-less Amphibians (Anoura). 



THORAX (Gr. a breastplate). The chest. 



THREAD-CELLS. (See Cnidae. ) 



THYSANURA (Gr. thusanoi, fringes ; and oura, tail). An order of Apterous 

 Insects. 



TIBIA (Lat. a flute). The shin-bone, being the innermost of the two bones of 

 the leg, and corresponding with the radius in the anterior extremity. 



TOTIPALHAT^; (Lat. totus, whole ; palma, the palm of the hand). A group 

 of Wading Birds in which the hallux is united to the other toes by mem- 

 brane, so that the feet are completely webbed. 



TOXODONTIA (Gr. toxon, bow ; odous, tooth). A distinct order of Mammals. 



TRACHEA (Gr. tracheia, the rough windpipe), The tube which conveys air to 

 the lungs in the air-breathing Vertebrates. 



TRACHEAE. The breathing-tubes of Insects and other Articulate animals. 



TRACHEARIA. The division of Arachnida which breathe by means of tracheae. 



TREMATODA (Gr. trema, a pore). An order of Scoledda. 



TRICHOCYSTS (Gr. tkrix, hair; and kustis, a cyst). Peculiar cells found in 

 certain Infusoria, and very nearly identical with the ''thread- cells" of 

 Codenterata. 



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



TRITOZOOID (Gr. tritos, third ; zoiin, animal ; and eidos, form). The zooid 

 produced by a deuterozob'id ; that is to say, a zooid of the third generation. 



TROCHAL (Gr. trochos, a wheel). Wheel-shaped ; applied to the ciliated disc 

 of the Rotifera. 



TROCHANTER (Gr. trecho, I turn). A process of the upper part of the thigh- 

 hone (femur) to which are attached the muscles which rotate the limb. 

 There may be two, or even three, trochanters present. 



TROCHOID (Gr. trochos, a wheel ; and eidos, form). Conical with a flat base ; 

 applied to the shells of Foraminifera and Univalve Molluscs. 



TROPHI (Gr. trophos, a nourisher). The parts of the mouths in insects which 

 are concerned in the acquisition and preparation of food. Often called 

 " instrumenta cibaria. " 



TROPHOSOME (Gr. trepho, I nourish ; and soma, body). Applied collectively 

 to the assemblage of the nutritive zooids of any Hydrozob'n. 



TRUNCATED (Lat. trunco, I shorten). Abruptly cut off; applied to univalve 

 shells, the apex of which breaks off, so that the shell becomes "decol- 

 lated." 



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." 



TURBELLARIA (Lat. turbo, I disturb). An order of Scoledda. 



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



ULNA (Gr. oleng, the elbow). The outermost of the two bones of the fore-arm, 



corresponding with the fibula of the hind-limb. 

 UMBELLATE (Lat. umbella, a parasol). Forming an umbel i.e., a number of 



nearly equal radii all proceeding from one point. 

 UMBILICUS (Lat. for navel). The aperture seen at the base of the axis of 



certain univalve shells, which are then said to be "perforated" or " um- 



bilicated." 



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

 UMBRELLA. The contractile disc of one of the Lucernarida. 

 UNCINATE (Lat. uncinus, a hook). Provided with hooks or bent spines. 

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

 UNCULATA (Lat. ungula, hoof). The order of Mammals comprising the 



Hoofed Quadrupeds. 

 UNGULATE. Furnished with expanded nails constituting hoofs. 



