20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I42 



The interest here is not so much in the presence or absence of in- 

 dependent radial elements as in the history of two of these, the inner- 

 most and outermost, in certain lower teleostean groups. Among the 

 isospondylous fishes the inner radial may be large (as in Salmo, fig. 

 6A, and Tarpon), small (as in Hiodon and Yarrella), or apparently 

 absent (as in Esox and Umbra). However, in all the isospondylous 

 fishes examined it is either absent or has a movable articulation with 

 the base of the innermost ray. 



In apparently the great majority of iniomous fishes, by contrast, 

 this inner radial becomes fused to the lower half of the innermost 



Fig. 6. — A, Pelvic girdle of larval salmon (Clupeiformes). (From Sewertsoff, 

 1934, fig. 26.) 



B, Innermost right pelvic ray of Myripristis (Beryciformes). The front of 

 the fish is toward the top, and the bottom of the fish is to the left of the figure. 



pelvic ray (Gosline, in press). As a result of this, the two or three 

 rays lateral to the innermost ray appear to articulate with a club- 

 shaped basal extension (as in fig. 6B) of the inner ray. As has been 

 pointed out (Gosline, in press), this fusion of radial and ray is not 

 invariable in the iniomous fishes. The known exceptions occur in 

 Alepisaurus where the inner pelvic ray and radial are attached but 

 not fused to one another, and in Bathypterois where the two structural 

 elements movably articulate with one another as in most isospondylous 

 fishes. 



In both Halosauropsis and Notacanthus of the Notacanthi formes 

 the innermost ray of the pelvic fin articulates movably with the inner 

 radial as in isospondylous fishes. The same condition holds for 

 Brycon among the ostariophysine fishes. 



By contrast there are several orders in which the bottom half of 

 the innermost pelvic ray has the club-shaped (radial) extension 

 typical of the iniomous fishes. Among these are at least the Percopsi- 



