EXPLANATION OF PLATE 19.
Complete List of Reference Letters.
Nervous System.
n. Nerve. spn. Spinal nerve. syg. Sympathetic ganglion.
Alimentary Canal.
cl. Cloaca. incl. Cloacal involution. œep. Œsophageal epithelium. pan. Pancreas. th. Thyroid body.
General.
abp. Abdominal pocket (pore). aur. Auricle. cav. Cardinal vein. cauv. Caudal vein. ly. Lymphoid tissue. mm. Muscles. od. Oviduct. pc. Pericardium. pp. body-cavity. sr. Suprarenal body. u. Ureter. vao. Ventral aorta (anterior continuation of bulbus arteriosus). ven. Ventricle. wd. Wolffian duct.
Figs. 1a, 1b, 1c. Three sections through the cloacal region of an embryo belonging to stage O. 1a is the anterior of the three sections. Zeiss A, ocul. 2. Reduced one-third.
1a shews the cloacal involution at its deepest part abutting on the cloacal section of the alimentary tract.