no. 3647 PERCIFORM FISHES — GOSLESTE 23 



ing Gadopsis, only those features not previously considered, in which 

 it differs from the ophidioids, will be mentioned. In addition, in view 

 of the recent reassignment of the ophidioids and zoarcids to the 

 Gadiformes by Greenwood, et al. (1966), it seems necessary to discuss 

 once again some of those features that provide the basis for believing 

 that the similarities among these three groups are due to convergence 

 and not to genetic inheritance. 



Jaw structure. — In addition to characters already discussed, two 

 other aspects of ophidioid jaw structure will be noted herein. First, 

 most, if not all, of the brotulids and ophidiids retain a supramaxillary. 

 In this minor feature, Gadopsis has advanced farther from the basal 

 percoid condition, for it has no supramaxillary. Second, Gadopsis and 

 the ophidioids, like most percoids, have the premaxillary subequal to 

 the maxillary in length. In this they differ from such groups as the 

 zoarcids, uranoscopids, and batrachoids, which often have very short 

 premaxillaries and the much longer maxillaries to some extent included 

 in the gape. 



Suspensorium and associated structures. — The major peculiar- 

 ity of the suspensorium of Gadopsis and the ophidioids is a trend to- 

 ward the fusion of the mesopterygoid and ectopterygoid. This fusion, 

 which seems to be a constant feature of ophidiids, pyramodontids, 

 and carapids (see Regan, 1912d, and Gosline, 1960) occurs in Gadopsis. 

 Here again, Gadopsis is somewhat more advanced than brotulids, in 

 which, so far as known, the ectopterygoid and mesopterygoid are 

 separate. 



The suspensorium of the gadiform fishes and its innervation is very 

 different from anything found in Gadopsis, the ophidiids, or, for that 

 matter, in the percoid fishes. Regan (1903b, p. 464) has commented on 

 some of the gadiform peculiarities as follows : 



Certain features of the suspensory apparatus seem to be constant throughout the 

 suborder, and may prove to be of some importance. The head of the hyomandibu- 

 lar articulates with a single socket, to the formation of which the squamosal 

 and postfrontal contribute. The entopterygoid is well developed, attached to the 

 ectopterygoid below and in front by a vertical suture to the palatine. The palatine 

 is attached anteriorly only to the praefrontal, and has a long maxillary process 



By contrast, Gadopsis and other ophidioids have two more or less 

 separate articular heads on the hyomandibular, and the mesopterygoid 

 (entopterygoid) is attached to and forms a continuous surface with 

 the metapterygoid and sometimes posteriorly with the hyomandibular. 

 The most peculiar feature of the Gadiformes is the course of the 

 hyomandibular branch of the facial nerve. In most teleosts that have 

 been investigated (Patterson, 1964, p. 435), as in Gadopsis and ophidi- 

 oids, the hyomandibular branch and the main trunk of the facialis 

 nerve exit from the cranium by separate openings, that of the hyoman- 



