Branchial Muscles of Five Eel Families — Nelson 
349 
TABLE 1 
Muscles Attached to the Ventral Parts of the Gill Arches in Some Eels* 
GENUS 
Ol 
02 
03 
Rl 
R2 
R3 
R 4 
RC 
AT 
PT 
PC 
s 
VR 
A5 
SP 
Conger 
X 
X 
X 
- 
- 
- 
X 
X 
X 
X 
X 
X 
X 
X 
- 
Anguilla 
X 
X 
X 
- 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
- 
Moringua 
X 
X 
X 
- 
- 
- 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Kaupichthys 
- 
- 
- 
- 
- 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Uropterygius 
- 
X 
X 
X 
X 
- 
X 
Gymnothorax 
- 
- 
- 
- 
- 
- 
- 
- 
X 
X 
X 
X 
X 
- 
X 
* A5, Adductor 5; AT, transversus anterior; Ol-3, obliqui 1-3; PC, pharyngo-clavicularis; PT, transversus posterior; 
Rl-4, recti 1-4; RC, rectus communis; S, sphincter oesophagi; SP, subpharyngealis; VR, retractor ventralis. X, Muscle 
present; -, muscle absent. 
of C4-5. A sphincter (S) encircles the esopha- 
gus and also interconnects C5 of either side. 
Internal to the sphincter extend longitudinal 
fibers tending to separate anteriorly, forming 
a paired muscle, the ventral retractor (VR), 
attaching to LP and posteriorly extending some 
distance in the esophageal wall. 
Dorsal muscles are shown in Figure 2 and 
listed in Table 2. External levators (ELl-4) 
occur on arches 1-4, extending between the 
cranium and the proximal ends of El-4. In- 
ternal levators (ILl-2) occur on arches 1-2. 
ILl extends between the fascia of the trunk 
and 12. Inferior obliques (102-3) intercon- 
nect El -3. A small accessory oblique (AO) 
extends between El and 12. A superior oblique 
(SO) extends between E3 and 1 3. An adductor 
(A4) extends between E4 and C4. A posterior 
oblique (PO) extends between E4 and C5. 
The sphincter (S) encircles the esophagus and 
its anterior portion extends between the arches 
of either side. Internal to the sphincter occurs 
a longitudinal layer tending to separate an- 
terior, forming a paired muscle, the dorsal 
retractor, attaching to UP4 and posteriorly 
extending some distance in the esophageal wall. 
Anguilla 
Muscles are shown in Figures 3 and 4 and 
listed in Tables 1 and 2. They are rather simi- 
lar to those of Conger and have been studied 
by Dietz (1912) and Kesteven (1943), whose 
terminologies are compared with that used 
here in Tables 3 and 4. In the second arch, that 
portion of the oblique (02) inserting on Hi 
corresponds to a rectus (Table 1, R2). A 
posterior transversus (Table 1, PT) is repre- 
sented by the anteroventral portion of the 
sphincter (S). 
Morin gua 
Muscles are shown in Figures 5 and 6 and 
listed in Tables 1 and 2. A major feature of 
the musculature is the subpharyngealis (SP), 
a sheet of longitudinal fibers dorsal to the ven- 
tral arch elements. A transverse (Fig. 6, TD) is 
partly distinct from the anterodorsal part of the 
sphincter. 
Kaupichthys 
Muscles are shown in Figures 7 and 8 and 
listed in Tables 1 and 2. With some minor 
differences the muscles are most similar to those 
of Morin gua. 
TABLE 2 
Muscles Attached to the Dorsal Parts of the Gill Arches in Some Eels* 
GENUS 
ELI 
EL2 
EL3 
EL4 
IOl 
102 
103 
AO 
ILl 
IL2 
so 
PO 
A4 
DR 
s 
MP 
LP 
PP 
Conger 
X 
X 
X 
X 
- 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
- 
- 
- 
Anguilla 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
- 
- 
- 
Moringua 
X 
X 
- 
X 
X 
X 
X 
- 
X 
X 
X 
X 
X 
X 
X 
- 
- 
- 
Kaupichthys 
X 
X 
X 
- 
X 
X 
X 
- 
X 
X 
X 
X 
X 
X 
X 
- 
- 
- 
Uropterygius 
- 
- 
Hj 
- 
- 
X 
X 
- 
X 
- 
- 
- 
X 
X 
X 
X 
- 
X 
Gymnothorax 
X 
X 
X 
- 
X 
X 
X 
- 
X 
X 
- 
- 
X 
X 
X 
X 
X 
- 
* A4, Adductor 4; AO, obliquus inferior accessorius; DR, retractor dorsalis; ELl-4, levatores externi 1-4; ILl-2, 
levatores interni 1-2; 101-3, obliqui inferiores 1-3; LP, protractor lateralis; MP, protractor medialis; PO, obliquus pos- 
terior; PP, protractor posterior; S, sphincter oesophagi; SO, obliquus superior. X, Muscle present; -, muscle absent. 
