The shaded part in 4 is the -otic capsule- [tympanum]. The hyoid apparatus is roughly represented in black to show its relation to IX. (dorsal to it) and sp. 1 (ventral). Compare {nerves} IX and XII in Sheet 9. The nerves are numbered. cb., the cerebellum. c.h., cerebral hemispheres. f.t., filum terminale. g.tr., ganglion on the fifth nerve. l.t., lamina terminalis. mb., mid-brain. md., medulla oblongata. o.l., optic lobes. pin., pineal gland. pit., pituitary body. r.h., olfactory lobes (rhinencephalon). th.c., thalamencephalon. sp.1, first spinal nerve. sp.2, 3, brachial plexus to fore limb. Figure 5. The spinal column (and pelvic girdle) of the Frog. Figure 5b. Vertebrae. Figure 6. The pectoral girdle and limb, dorsal view. Figure 7. The pelvic girdle and right limb from the side. (l.h. shows the position of the right lymph hearts-- they are paired.) as., astragalus. b., body. c., calcar (?= a sixth digit). cal., calcaneum. cl., clavicle overlying a procoracoid cartilage. co., coracoid. f., fibula. [FE., femur.] h., humerus. il., ilium. is., ischium. o.st., omosternum. pu., pubis. r., radius. sc., scapula. s.sc., supra-scapula. s.v., sacral vertebra. t., tibia. t.p., transverse process. ul., ulna. ur., urostyle. x., xiphisternum. z., zygapophysis. 1, 2, and etc., first, second, and etc., digits. D. and D'. are simplified diagrams of the limbs for comparison with the similar ones of the Rabbit. In each girdle we have a dorsal ossification (scapula, ilium) and two ventral parts (pubis and procoracoid cartilage, ischium and coracoid), and at the meeting-place of the three in each case the proximal bone of the limb (humerus, femur) articulates. {Illustration: Diagram Sheet 12.} Sheet 13. -Urogenital Organs of the Frog_. Figure 1. The Male. Figure 2. The Female. The oviduct removed on the animal's left, and the ovary on its right. Organs common to both sexes.-- al.b., allantoic bladder. c.ad., corpus adiposum. cl., cloaca. int., intestine. K., kidney. lg., (dotted outline of) lung. oes., oesophagus. r.p.v., renal portal vein. st., stomach. In the Male.-- T., testis. v.e., vasa efferentia. u.g.d., urogenital duct. p., prostate gland. In the Female.-- adr., adrenal. f.t., fallopian tube (anterior part of oviduct). * its opening. o.d., oviduct (letters on [the opening] -uterine portion-). ov., ovary. ur., ureter. (This would be the condition about midwinter.) In March o.d. will be either enormously distended with eggs, or large, flabby, and empty, and ov. will be small and brownish, without any large eggs; the ovary gradually recovers its size through the summer. Figure 3. Spermatozoa attached to the parent cell (g.e.) from the lining epithelium of the testis, and one free. fl., the flagellum. {Illustration: Diagram Sheet 13.} Sheet 14 -Skull Structure and Development of the Frog_. Figure 1. I., II., early and late stages of the Tadpole's chindrocranium. Diagrammatic.