918 
UU. A. ERASER OiST THE DEVELOPMENT Of THE 
Explanation of the Figures. 
All the figures were drawn (with the exception of the last two) with a Zeiss’ 
camera (Oberhauser) and Hartnack objective. The numbers attached indicate in 
diameters the magnifying power employed. Some of the drawings are from single 
sections, hut the majority have been made by combiniug consecutive sections. 
The outlines iu such cases were generally drawn from a single section, and are 
strictly accurate. The details were filled in from the appearances seen with a Zeiss 
Obj. A, Ocul. 2X55, or with Obj. D, Ocul. 2X235. 
They have been restricted to those essential to the work in hand. 
Alphabetical List of Reference Letters. 
au.v. Auditory vesicle. 
a.st. Arteria stapedialis. 
ao. Aorta. 
a.st.m. Arteria stapedio-maxiHaris. 
a.c.c. Arteria carotis communis. 
a.c.i. Arteria carotis interna. 
a. v. Arteria vertebralis. 
art.i.st. Articulation between incus and 
stapes. 
art.bp. Articulation between bulla and 
petrosal. 
B. Bulla. 
Br\ First branchial arch. 
Br 2 . Second branchial arch. 
b. cr. Basis cranii. 
ch.t. Chorda tympani. 
ch. Chorda dorsalis. 
c. co. Canalis cochlearis. 
c.he. Cerebral hemispheres. 
ce. Cerebellum. 
e.s.ca. External semicircular canal. 
fbr. Fore brain. 
fl. Fore limb. 
fe.r. Fenestra rotunda. 
G.ga. Ganglion gasserii. 
g.v.ac. Vestibular portion of ganglion 
acusticum. 
g. c.ac. Cochlear portion of ganglion 
acusticum. 
h. br. Hind brain. 
hy.c. Hyoidean cartilage. 
Ily. Hyoid arch. 
II. Heart. 
in. Incus. 
in.m. Investing mass. 
la. Lamina of papery bone between 
mandibular process of malleus 
and tubercle at the junction 
of the neck with the manu¬ 
brium (the free edge of which 
is called by Doran processus 
gracilis). 
m.au.e. Meatus auditorius externus. 
mn.c. Mandibular cartilage. 
ran. Mandible. 
m. Malleus. 
raa.h. Head of malleus. 
ma.n. Neck of malleus. 
m.ma. Manubrium mallei. 
m.obl. Medulla oblongata. 
