382 APPENDIX III 



THYMUS (G. thymon, thyme), a gland of lymphoid tissue, arising as 

 proliferations of cells from the gill pouches, and migrating poste- 

 riorly (in the mammal). 



THYROID (G. thyreos, a shield), an endocrine gland arising as a median 

 evagination from the floor of the pharynx; homologous with the 

 endostyle. 



TOMA (G. a section), a suffix, meaning a cut or segment; sclerotome; 

 mj'otome. 



TRABECULA (L. a Small beam), a supporting band of connective tissue; 

 also, the finger-hke cartilaginous processes during the development 

 of bone. 



TRACHEA (G. trachys, rough), the windpipe from the glottis to the bifurca- 

 tion. 



TREMA (G. an opening), a combining form; monotreme, post trematic, 

 pretrematic. 



TRi (L. three), a prefix; trituberculate, tricuspid. 



Triassic (G. trias, from treis, three), a geological period of the Mesozoic, 

 the lowest strata, followed by the Jurassic and Cretaceous. 



TUBER (L. a swelling), a rounded swelling or prominence; tuber cinerium. 



TUNIC (L. tunica, a tunic), a covering or investing sheet, the tunic of the 

 testis; also as a combining form, Tunicata. 



TuNiCATA (L. tunica), a sub-phjdum of chordates, the Urochordata. The 

 tunicates have a notochord in the tail region during embryonic life, 

 then become sessile and develop a tunic. 



TURCICA (L. Turcus, Turk), in sella turcica, the Turk's saddle; see sella. 



TYMPANIC (G. tympanon, a drum), a drum-like membrane; specifically, 

 the ear drum, or tympanum. 



ULNA (L. ulna, elbow), the post-axial bone of the forearm, against which 

 fits the humerus; its proximal end is the olecranon process. 



UMBILICAL (L. umbilicus, navel), pertaining to the umbilicus; the umbilical 

 cord connects the embryo with the placenta. 



Ungulata (L. ungula, a hoof), an artificial grouping of mammals, includ- 

 ing those which walk on the tips of their toes (the orders Artiodactjda 

 and Perissodactj'la). 



unguligrade (L. ungula, a hoof, plus gradior, to walk), a foot position, 

 with the sole of the foot entirely off the ground, and standing on the 

 tips of the toes. 



UNI (L. one), a prefix; unilateral, uniform. 



URA (G. oura, tail), a combining form; Urodela, Anura. 



URETER (G. ouron, urine), the metanephric duct leading from the kidney 

 to the urinary bladder. 



URETHRA (G. ouron, urine), the duct leading from the bladder to the 

 outside; in the male it is joined by the vasa deferentia. 



URINOGENITAL (L. wina, urine, plus genitalis, genital), the organs as- 

 sociated with the excretory and reproductive functions. 



Urodela (G. oura, plus delos, evident), an order of amphibia with a 

 well developed tail, including salamanders, newts, and the gilled 

 amphibia. 



UTERUS (L. the womb), a mammalian structure homologous with the 

 oviducts, in which the embryos develop. 



