MATARESE ET AL.: LARVAL DEVELOPMENT OF PACIFIC TOMCOD 



NS 



FIGURE 3.— Development of the caudal fin oiMicrogadus proximus: A. 5.2 mm SL; B. 7.8 mm SL: C. 9.5 mm SL; D. 10.5 mm SL; E. 1 1.9 

 mm SL; F.15.8 mm SL; G. 25.0 mm SL; H. 41 . 1 mm SL. AUG = anterior ural centrum; EP = epural; HS = haemal spine; HY = hj^pural; 

 NG = notocord; NS = neural spine; PG = preural centrum; PUG = postural centrum; TPG = terminal preural centrum. Ossified 

 elements are stippled. 



three superior hypurals (Fitch and Barker 1972); 

 and 3) presumably more advanced families of 

 fishes in the same evolutionary line as gadids ( e.g., 

 order Batrachoidiformes) have tw^o hypurals, ap- 

 parently representing fusion of component parts 

 (Rosen and Patterson 1969). 



Barrington (1937), who figured and described 

 the development of the caudal fin in G. morhua, 

 provides the only other description of caudal de- 

 velopment in gadids. His illustrations also depict 

 only three hypural elements. Barrington, how- 

 ever, considered it unlikely that fusion of hypural 

 bones could occur without some evidence of com- 

 pound origin remaining in the fused bones. Our 



terminology of the caudal fin bones differs from 

 that used by Barrington ( 1937) for G. morhua. We 

 consider his ventral radial as hypural 1 and his 

 dorsal radials 1 and 2 to be epurals 1 and 2. 



Also we found no evidence of a uroneural in the 

 development of the caudal fin of M. proximus. 

 Rosen and Patterson ( 1969) consider the presence 

 of one uroneural as a characteristic of the 

 Gadiformes. 



An anlage of the first anal fin is evident by 8.7 

 mm SL and the base of the second anal fin is 

 present at 9.3 mm SL. Rays in the first anal fin 

 begin ossifying at about 11.9 mm SL and in the 

 second anal fin at 12.7 mm SL. Ossification is 



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