no. 3647 PERCIFORM FISHES — GOSLINE 25 



ramus lateralis pattern (Freihofer, 1963, p. 136). In this instance, then, 

 I would view the similarities in nerve course as an adaptive trait that 

 has been elicited more than once by similar circumstances. 



Pectoral. — In Gadopsis and ophidioids, there are four actinosts. 

 In the Gadiformes, the number varies from three to 13. The scapular 

 foramen of Gadiformes is usually between the scapula and coracoid; 

 in Gadopsis and ophidioids, it is contained in the scapula. 



Dorsal and anal fins. — It is in the structure of the vertical fins 

 that the percoid affinities of Gadopsis are most plainly manifest. In 

 that fish, there is a single dorsal fin with 10 pungent spines anteriorly, 

 followed by 27 or 28 soft rays. Anterior to the dorsal fin, there are two 

 well-developed predorsal bones, the anterior interdigitating between 

 the second and third neural spines and the posterior between the 

 third and fourth. The anal fin has three sharp, graduated spines at 

 the front of the fin and 18 or 19 soft rays. The pterygiophores of these 

 spines are separate, but the second is considerably enlarged and ex- 

 tends up in front of the first hemal arch. (One peculiarity of the dorsal 

 and anal fins of Gadopsis is that its last dorsal and anal rays are not 

 divided to the base.) 



Ribs. — In Gadopsis, Baudelot's ligament originates on the basioc- 

 cipital. There are epipleurals from the first vertebra and pleural ribs 

 from the third. The anterior pleural ribs are enlarged only slightly, 

 if at all. The gas bladder is large, firm walled, simple, and without 

 special ligaments to either the ribs or skull. In all these respects, 

 Gadopsis is typically percoid. 



The ribs of ophidioids are modified in various ways as already 

 noted. In one of the less-marked modifications, Brotula has epipleural 

 ribs from the first vertebra and pleural ribs from the third (Regan, 

 1912d, p. 278). Baudelot's ligament is attached to the basioccipital; 

 however, in Brotula, the first two pleural ribs are expanded, and there 

 is a sheath of ligamentous tissue extending up and forward from the 

 gas bladder over the anterior ribs. In no known ophidioid is the first 

 vertebra fused to the skull. 



The gadoids differ in the above features in several respects. There 

 are never any epipleural or pleural ribs on the first two vertebrae. 

 In most macrourids, the first vertebra is free from the skull and 

 Baudelot's ligament, so far as known, is attached to the first vertebra. 

 In the gadids, by contrast, the neural arch of the first vertebra is 

 attached firmly to and its centrum completely fused into the cranium; 

 here, Baudelot's ligament originates on the rear of the skull. Unlike 

 ophidioids, there may be a direct connection between the gas bladder 

 and inner ear in gadoids (in Moridae; Svetovidov, 1948), and when 

 the gadoids have "drumming muscles," these usually are not attached 

 to the ribs or skull (Marshall, 1965, pp. 312-313). 



