POTTHOFF: DEVELOPMENT AND STRUCTURE OF FINS IN CORYPHAENA 



purus was between 7 mm NL and 7.5 mm SL, and 

 in C. equiselis between 6.5 mm NL and 7.6 mm SL 

 (Figure 19). During the flexion stage of some 

 C. hippurus the neural spine of preural cen- 

 trum 3, the speciaHzed neural arch of preural 

 centrum 2, and the two epurals began to develop 

 from cartilage (Figure 19). Hypural 5 was first 

 seen in cartilage at 8.1 mm SL. The two paired 

 uroneurals did not develop from cartilage — in 

 C. hippurus the larger, more ventrally and ante- 



ognized only one epural for adult C. hippurus. In 

 Coryphaena spp., hypurals 1 and 2 and hypurals 3 

 and 4 fused to a dorsal and ventral hypural plate 

 (Figures 20-23, Table 10). During fusion paired 

 bony ventrolateral and dorsolateral articular pro- 

 jections formed on the ventral edge of hypural 3 

 and on the dorsal edge of hypural 2. These 

 projections became the articulatory surfaces be- 

 tween the dorsal and ventral hypural plates (Fig- 

 ures 20-23). The two hypural plates of Cory- 



EpS-.— Un 



Figure 19. — Supporting bones of the caudal complex of Coryphaena hippurus (right) 

 7.6 mm SL and C. equiselis (left) 7.6 mm SL. Symbols: Eps, epurals; Hs, haemal spine; 

 Hy, hypural; "Na", specialized neural arch; Ns, neural spine; Ph, parhypural; Pu, preural 

 centrum; Un, uroneural; Ur, urostyle. Stippled, cartilage; darkened, ossifying bones; 

 stippled darkened areas are cartilage just beginning to ossify. 



riorly located pair was seen at 8-10.6 mm SL, and 

 the smaller, more dorsally and posteriorly located 

 pair was seen at 11.9 mm SL. Development of the 

 two paired uroneurals occurred at a smaller size in 

 C. equiselis (Figure 19 left. Table 10). The smaller 

 uroneural pair gradually fused to the outside of 

 the larger uroneural pair in both species. This 

 fusion was completed between 75 and 85 mm SL 

 for C. hippurus and between 75 and 80 mm SL 

 for C. equiselis (Table 10). Monod (1968) recog- 

 nized only one uroneural (stegural) pair in adult 

 C. hippurus. 



Ossification of the cartilage bones in the caudal 

 complex of C hippurus began with the urostyle at 

 8 mm SL. Last to ossify at 14.6 mm SL were the two 

 epurals. The ossification sequence of all hypural 

 bones is shown in Table 10. The epurals of C. 

 hippurus developed and fused in the same manner 

 as those of C. equiselis, although development and 

 fusion were always at a smaller size for C. equi- 

 selis (Figures 19-23, Table 10). Monod (1968) rec- 



Eps 



0.5 mm 



FIGURE 20.— Supporting bones of the caudal complex of Cory- 

 phaena equiselis, 11.0 mm SL. Symbols: Uns, uroneurals. For 

 explanation of other symbols, see Figure 19. Stippled, articular 

 cartilage; darkened, bone. 



297 



