_tv_, _tv'_, third ventricle of brain. _ty_, thymus gland. _u_, umbilical stalk. _v'_, _v''_, _v'''_, first, second, and third cerebral vesicles. _va_, vascular area. _vc_, vocal cords. _vm_, vitelline membrane. _vn_, ventricle of heart. _vp_, velum palitum. _vv_, vitelline blood vessels. _wd_, Wolffian duct. _wdo_, opening of Wolffian duct. _wr_, Wolffian ridge. _wt_, Wolffian tubule. _x_, point of origin of bronchi. _y_, yolk. _ys_, yolk-stalk. [Transcriber's Note: The Figures were printed on a series of 15 pages ("Plates") at the end of the book. Since the caption text has already been given in full, the individual Figure numbers will not be repeated here.] * * * * * * * * * * * * * * Errata As seen in figure 6A the lungs are irregularly conical _printed as 6a_ at the point marked _X_ _text [two occurrences] unchanged: capital letter not explained_ _ep_, epidermal layer of ectoderm. [. for ,] _epi_, pineal body. [_epi_ not italicized]