Sheet 12.

Figure 1. Upper view of the Frog's brain.
Figure 2. Under view of the same.
Figure 3. The same-- median section.
Figure 4. The distribution of the Frog's nerves.
Compare [Sheet 9], Figure III.
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.

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.