Ophichthid Eels — Gosline 
305 
rich. 
marily because of this difference, Regan 
( 1912 ) has, by implication, postulated these 
two families as being near the starting points 
of the two main lines of eel evolution. The 
ophichthids belong in the congrid line. 
In Conger the suspensorium is well de- 
veloped and its bones are well integrated, 
i. e., the palatopterygoid is united by suture 
with both the quadrate and the hyoman- 
dibular. The opercular bones are all large and 
well developed for eels. The branchiostegals 
are few (9-9), and those of the two sides do 
not overlap on the mid-line. The large basi- 
hyal projects into the free tongue. These are 
all primitive characters as compared with the 
Ophichthidae. Conger and Anguilla agree in 
having the skull long and low (this does not 
seem to me to be a necessarily primitive 
feature) and in certain associated bone ar- 
rangements, i. e., the interorbital opening, 
alisphenoids, and pterotics are longitudinally 
elongate, and the orbitosphenoid is small or 
absent externally. Unlike most ophichthids, 
but like Anguilla, Conger h.2iS the suspensorium 
forwardly inclined, and has the intermaxillary 
and vomerine teeth in an almost continuous 
series. Unlike most eels that I have examined, 
including the ophichthids. Conger lacks the 
cross commissure of the lateral line system in 
the frontals that gives rise to a middorsal pore. 
The head skeleton of the Ophichthidae dif- 
fers from that of Conger in four principal ways : 
(1) there has been a further reduction in the 
size and strength of certain of the skull bones; 
(2) the suspensorium has become nearly or 
quite vertical; (3) the branchiostegal rays 
have developed a basketlike arrangement on 
the throat; and (4) an auditory bulla is 
present. 
The bones that have undergone further re- 
duction are the palatopterygoid, the elements 
of the opercular series, and the preorbital. 
It is impossible to say, but seems probable, 
that the change from a forwardly inclined 
suspensorium in Conger to the nearly vertical 
one of the Ophichthidae is functionally re- 
lated to the inferior mouth of most ophich- 
thids. At any rate, in Conger much of the 
adductor muscle of the mandible runs up- 
ward and backward to attach to an aponeuro- 
sis on the posterodorsal angle of the skull. 
In the Ophichthidae (with a vertical suspen- 
sorium and a more posterior articulation of 
the mandible) the adductor muscles run more 
directly up over the skull, and the postero- 
dorsal crest of Conger is reduced or totally 
absent. In addition, the opercular muscula- 
ture, which attaches to the rear of this same 
crest in Conger, is much reduced in the 
Ophichthidae. Thus, the skull of the ophich- 
thids, instead of ending posteriorly in an 
acute edge, usually tapers off more or less 
gradually into the vertebral column. 
Certain other changes in the head skeleton 
appear to be related to the backward dis- 
placement of the quadtate in ophichthids. 
The maxillary, the posterior end of which 
abuts against the dentary in Conger, usually 
falls far short of this bone in ophichthids and, 
except in Brachysomophis, is attached to the 
mandible only by a long, slender, and some- 
times ossified ligament. Also, in ophichthids, 
the palatopterygoid has lost its importance as 
a strut between the suspensorium and the 
skull, and has become more or less reduced 
and disarticulated. 
In Conger, with forwardly suspended jaw 
and moderately well- developed opercular ap- 
paratus, the gill arches lie largely below the 
skull, and the gill openings are less than a 
skull length behind. In ophichthids, on the 
other hand, the gill arches lie mostly behind 
