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A, anastomosis 
B, buccal cavity 
b, attachment of jaw bar to hyoid 
Br, brain 
C, cornual cartilage 
D, skin 
d, dorsal spinal nerve 
E, endostyle 
Hi, eye 
G, gills 
H, hyoid 
H’, hyoidean procartilage 
Hs, hyoid arch 
Hy, hypophysial canal 
J, jaw bar 
Jd, dentigerous jaw cartilage 
Jl, jaw ligament 
Jo, median ventral jaw bar 
L, left side 
l, left median tentacle 
li, ligament 
M, myotome 
mc, circular velar muscle 
mn, nasalis muscle 
Me, endostyle muscle 
Md, mandibular nerve 
Mj, jaw muscle 
Mn, ventral transverse muscle 
mr, radial velar muscle 
mv, velar muscle 
Mzx, maxillary nerve 
N, nasalis nerve 
n, nerve 
Na, nose 
Ne, notochord 
NI, nasal capsule 
No, nasal canal 
HOWARD AYERS 
ABBREVIATIONS 
Nov, velar nerve 
O, oral hood 
ol, ophthalmic lateralis nerve 
on, ophthalmic nerve 
opth, ophthalmic nerve 
os, oral sphincter 
P, palatine 
Pc, palato-coronarius muscle 
Pl, plexus of jaw apparatus 
Q, quadrate 
R, right side 
r, right median tentacle 
Rm, rectus muscle 
S, subnasal bar 
Se, septalis nerve 
sm, myoseptum 
sp, Occipitospinal nerves 
T, tentacle 
t, thyroid 
Te, terminalis nerve 
Tm, median tentacle of Ammocoetes 
U, upper lip 
Ul, lower lip 
V, velum 
v, ventral spinal nerve 
ve, velar chamber 
Vl, velar ligament 
Vn, velar nerve 
vg, veloquadratus muscle 
W, wall of oral hood 
I to V, jaw muscles of Amphioxus 
VII, facial nerve 
VIII, a and b, two acusticus nerves to 
snout complex 
IX, glossopharyngus nerve 
X, vagus nerve 
Figs. 1 to 13, except fig. 10, Amphioxus. 
Figs. 14 to 21, Ammocoetes. 
Figs. 22 to 36, except fig. 30, Bdellostoma. 
Fig. 30, Chimaera. 
Fig. 10, Callorhynchus. 
