682 -GLOSSARY. 



produced by a deuterozooid ; that is to say, a zooid of the third genera- 

 tion. 



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- 

 bone (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 mouth in insects whicli 

 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 Hydrozoon. 



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 Scolecida. 



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



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

 arm, corresponding with theJiMa 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 " urn- 

 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. 



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 ; valvce, folding-doors). A shell composed of a 

 single piece or valve. 



URODELA (Gr. oura, tail ; ddos, visible). The order of the tailed Amphi- 

 bians (Newts, &c.) 



URTICATING CELLS (Lat. urtica, a nettle). (See Cnidae). 



VACUOLES (Lat. vacuus, empty). The little cavities formed in the interior 

 of many of the Protozoa by the presence of little particles of food, usually 

 surrounded by a little water. These are properly called " food-vacuoles," 

 and were supposed to be stomachs by Ehrenberg. Also the clear spaces 

 which are often seen in the tissues of many Ccelenterata. 



VARICES (Lat. varix, a dilated vein). The ridges or spinose lines which mark 

 the former position of the mouth in certain univalve shells. 



VASCULAR (Lat. vas, a vessel). Connected with the circulatory system. 



VELUM (Lat. a sail). The membrane which surrounds and partially closes the 

 mouth of the " disc " of Medusa, or medusiform gonophores. 



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

 body. 



VENTRICLE (Lat. dim. of venter, stomach). Applied to one of the cavities of 

 the heart, which receives blood from the auricle. 



