GLOSSARY 703 



Tentaculocyst. The sense organs of the Scyphozoa. 



Terminal. Towards or at the posterior or the distal end. 



Test. The tunic of the ascidian; the rigid shell of the sea-urchin. 



Testis. The male sexual gland. 



Theca. The outer wall of the calcareous cup of a stony coral. 



Thorax. The body-division just anterior to the abdomen. 



Tiedemann's vesicles. Minute diverticula of the ring canal of the starfish. 



Tooth papillae. Projections from the jaw of a brittle star. 



Trachea. A respiratory tube in air-breathing arthropods. 



Trichocyst. A cyst containing a defensive bristle in the ectosarc of infusorians. 



Trochophore. A larval form common to annelids, mollusks, and other animals. 



Trophi. The paired jaws in the mastax of rotifers. 



Trophosome. The hydroid stage of hydromedusans. 



Trophozooid. The youthful stage of a fungoid coral. 



Tunic. The outer cuticular covering of tunicates. 



Umbilicus. A depression or cavity at the axial base of a snail shell. 



Umbo. The protuberance above the hinge on the shell of a pelecypod. 



Ureter. A tube forming the outlet of the kidney. 



Uropod. The sixth swimmeret of certain crustaceans which forms the swim- 

 ming tail. 



Uterus. A dilated portion of the oviduct in which the egg or the developing 

 animal may be held. 



Vagina. The terminal division of the female reproductive tract. 



Vas deferens. A duct leading from the testis towards the external opening; 

 the sperm-duct. 



Vegative organs. Those organs which have to do with the processes of nutri- 

 tion, growth, and the expulsion of wastes. 



Vein. A vessel which brings blood towards the heart. 



Velarium. The false velum of Cubomedusae. 



Veliger larva. The larva of many gastropods. 



Velum. The circular muscular locomotory membrane of a hydromedusan. 



Ventral. On or towards the underside of an animal. 



Ventricle. A chamber of the heart from which blood is sent over the body. 



Vesicula seminalis. A sperm-sac in the male animal. 



Vestibule. The depression within the lophophore in entoproct bryzoans. 



Vibraculum. Whip-like defensive organs in many bryozoans. 



Viscera. The organs within the body-cavities. 



Visceral mass. The compact group of organs comprising the principal viscera 

 in mollusks. 



Winter eggs. Thick-shelled eggs produced by parthenogenetic females after 

 fertilization, usually in the fall. 



Zodchlorellae. Single-celled algae which live symbiotically with some inverte- 

 brates. 

 Zocecium. The outer cuticular covering of a bryozoan. 



