POTTHOFF: DEVELOPMENT AND STRUCTURE OF FINS IN CORYPHAENA 



Figure 6. — Ontogenetic development of a dorsal fin pterygiophore with its serially associated ray in the 

 14th intemeural space of Coryphaena equiselis (left lateral view). Pterygiophores drawn in the natural 

 attitude relative to horizontal body axis. Starting from the left specimen length (millimeters SL) was: 

 top, 7.6, 9, 9.8, 11.5, 12.2, 14.2; bottom, 17.4, 22.5, 45.4, 31. Symbols: D, distal radial; P, proximal radial; 

 R, serially associated ray. Stippled, cartilage; darkened, bone. 



a ray developing concurrently (Figures 2, 10, 11). 

 In specimens of both species, which had the full 

 count of pterygiophores in the first intemeural 

 space, it was common to have a ray develop in 

 front of the cartilaginous pterygiophore (Fig- 

 ure 2). The pterygiophores of the first intemeural 

 space in large juveniles and adults of both species 

 were vertical to the body axis near the first neural 

 spine and slightly anteriorly inclined dorsad near 

 the head (Figure 12). The anteriormost pterygio- 

 phore in the adults was either of normal size (not 

 figured), very small (Figures 12, 13), or just a 

 vestige (not figured). In a few instances, in both 

 species, the anteriormost pterygiophore was com- 



pletely or partially fused to the second pterygio- 

 phore. The anteriormost pterygiophore of both 

 species had either one, two, or three associated 

 rays (Table 2). For the two species the anterior- 

 most dorsal fin ray was either normal in size or a 

 vestige (Figures 12, 13). In both species three types 

 of first fin ray vestiges were observed: a paired 

 vestige (Figure 13), a single right vestige, and a 

 single left vestige. 



Distal radials were present between the bases of 

 each fin ray for almost the entire dorsal fin. Distal 

 radials were last to ossify from the distal portion of 

 the pterygiophore cartilage. Only the anterior- 

 most three fin rays of both species sometimes 



285 



