301 
Ophichthid Eels — GoSLiNE 
in Leiuranus. Here the two maxillaries have 
moved toward each other across the roof of 
the mouth until their forward ends abut 
against one another (Fig. Ah'). 
Fig. 4. Leiuranus semicinctus. a, Head bones from 
right. Bones as in Fig. 2b. h, Bones of roof of mouth 
from below, semidiagrammatic. Teeth indicated, im. 
Intermaxillary area of premaxillary-ethmo-vomer; ma. 
maxillary; rc, rostral cartilage; vo, vomerine area of 
premaxillary-ethmo-vomer. 
SKULL. In the cranium of the species examined 
the greatest difference is between Myrichthys 
and the others. In Myrichthys (Fig. 5) the 
snout is blunt and rounded and the skull is 
short and high. The interorbital opening 
seems to have been compressed from front 
to rear and is elongate vertically. The orbito- 
sphenoids are large, apparently filling that 
part of the skull wall left by the withdrawal 
upward of the frontals. In the other genera 
the interorbital opening is always longer than 
high. In those species with especially long, 
low skulls, e. g., Caecula platyrhyncha and 
Brachysomophis henshawi, the opening is almost 
slitlike, whereas in those with a moderately 
high skull, e. g., Muraenichthys cookei and 
Ctrrhimuraena macgregori, it is more rounded. 
In all but Myrichthys the orbitosphenoid ap- 
pears to be more or less squeezed out ex- 
ternally by the frontals above and the para- 
sphenoid below. 
In most of the Ophichthidae the ethmoid 
projects up over the dorsal surface of the 
frontals as a subtriangular median wedge 
(Fig. Ic). However, in Myrichthys (Fig. 5^) 
and Muraenichthys (Fig. 3^) the projection is 
broad and bilobed. 
Fig. 5. Myrichthys maculosus. a, Cranium from left; 
b, from above. Bones as in Fig. 1. 
In all the ophichthids examined, auditory 
bullae are developed as bulges on the ventral 
surface of the skull. These bullae are formed 
from parts of the basioccipitals, exoccipitals, 
and prootics. Axial muscles from the body 
attach especially to the basioccipitals which, 
in Brachysomophis, form a distinct lobe for this 
purpose (Fig. 2b). Auditory bullae are least 
prominent in Cirrhimuraena (Fig. 6b). 
Fig. 6. Cirrhimuraena macgregori. a. Head bones 
from right. Bones as in Fig. 2a. b. Skull from below. 
Teeth shown. Labels as in Figs, lb and Ab. 
