Note the kidneys, two elongated, flattened, dark-red bodies lying one on each side of the vertebral column towards the posterior end of the abdominal cavity. From the outer edge of each kidney a ureter arises and runs backward, opening into the cloaca on the dorsal side, opposite the opening of the urinary bladder. [_In the Frog the adrenal bodies may be seen on the ventral sides of the kidneys as small yellow patches._] In the male Platana note:-- (_a_) The testes, a pair of ovoid pale-yellow bodies attached to the dorsal wall of the body cavity by a fold of the peritoneum. They lie on the ventral sides of the kidneys and are connected to them by efferent vessels which pass into the kidneys. (_b_) The corpora adiposa or fatty bodies lying in front of the kidneys. (_c_) The ureters which run along the outside of the kidneys and unite posteriorly to form a single duct opening into the cloaca. [_In the Frog the ureters do not join together but open separately into the cloaca. Each ureter has a slight swelling, the vesicula seminalis, on its outer side._] [Illustration: FIG. 9--Male Urinogenital System of Xenopus and Rana.] In the female Platana note:-- (_a_) The ovaries, a pair of irregularly-lobed organs usually consisting of a mass of rounded black and white bodies, the ova. The ovaries are attached to the dorsal wall of the body cavity by a fold of the peritoneum. (_b_) The corpora adiposa lying in front of the kidneys. (_c_) The long convoluted oviducts opening into the body cavity in front and into the cloaca behind. The ureters open separately into the cloaca in the female. Make a drawing of the urinogenital system. [Illustration: FIG. 10.--Female Urinogenital System of Xenopus and Rana.] _Fifth Day._ =Skeletal System= (_continued_). A. The Pectoral and Pelvic Girdles and Limbs. 1. Detach a fore-limb with the remaining parts of the pectoral girdle. Make a preparation showing these various parts:-- Supra-scapula, scapula, remainders of the clavicle and the coracoid, humerus, radio-ulna, carpal bones, and digits. Draw these parts. [Illustration: FIG. 11.--Pectoral Girdle of Xenopus and Rana.] 2. Detach the pelvic girdle from the transverse processes of the 9th vertebra. Remove it with the hind-limbs from the body. Detach the femur from one side of the pelvic girdle, and make a sketch showing the following parts of the pelvic girdle:--Acetabulum, ilium, ischium, and pubis. [Illustration: FIG. 12.--Pelvic Girdle of Xenopus and Rana.] Make a preparation and a sketch showing the femur, tibia-fibula, astragalus, calcaneum and the other bones of the tarsal region, five metatarsals, and digits. Number the digits from the inner side. [Illustration: FIG. 13.--Hind and Fore Limbs of Xenopus.] B. The Vertebral Column.