Gill Arches of Teleostean Fishes — Nelson 401 
Figs. 41-44. 41, Uropterygius knighti. 42, Gymnothorax petelli. 43, G. petelli, pharyngeal jaws of right 
side, lateral view. 44, G. petelli, dorsal view. 
including Muraena, Echidna, Gymnothorax, 
and the remaining genera examined, are some- 
what more specialized in gill arch structure, 
having lost all hypobranchials. The lower tooth 
plates tend to lie on the medial surface of the 
proximal end of C4, which fits into a prominent 
groove in the plate. These two groups may be 
considered as distinct subfamilies within the 
family Muraenidae. 
uropterygiinae new subfamily 
Ossified hypobranchials in first and second 
arches ; lower pharyngeal tooth plates without 
a lateral groove ; retractor ossium pharyngealium 
muscles without an attachment to the vertebral 
column; anterior portion of dorsal aorta usually 
enclosed in a canal formed by vertebral pro- 
cesses; vertical fins reduced, with rays confined 
to the posterior part of the trail. 
