FISHERY BULLETIN: VOL. 78, NO. 2 



rent spur (Johnson 1975) was not observed in 

 either species. 



The caudal rays first developed in both species 

 from the midline between hypurals 2 and 3 in 

 preflexion larvae (Figure 17). Rays were added in 

 a posterior and anterior direction (Figure 18). 

 After complete notochord flexure the secondary 

 caudal rays were added in an anterior direction. 

 For equal-sized specimens from 6.5 mm NL to 19.5 

 mm SL, C. hippurus had fewer caudal fin rays 

 than C. equiselis (Table 9). 



Fnfid 



I- 



0.5 mm 



Figure 17. — Caudal complex of Coryphaena hippurus, 5.0 mm 

 NL. Symbols: Fnfld, finfold; Hs, haemal spine; Hy, hypural; 

 Nc, notochord; PCR, principal caudal ray; Ph, parhypural. 

 Stippled, cartilage; darkened, ossifying bones or rays. 



Caudal Fin Supports 



The caudal fin rays of Coryphaena spp. were 

 supported by some of the bones of the caudal com- 

 plex. Three posteriormost centra were involved in 

 this support. In 2 out of 97 C. equiselis the caudal 

 fin rays were also supported by a fourth centrum. 

 This variation was not observed in C. hippurus. 



Supporting bones of the caudal complex con- 

 sisted of three centra (urostyle and preural centra 

 numbers 2 and 3), one neural spine, one special- 

 ized neural arch, two autogenous haemal spines, 

 one autogenous parhypural bone, five autogenous 

 hypural bones, two paired uroneural bones, and 

 two epural bones. These parts were seen during 



0.5 mm 



Figure 18. — Caudal complex of Coryphaena hippurus, 6.0 mm 

 NL. For explanation of symbols, see Figure 17. Stippled, 

 cartilage; darkened, ossifying bones or rays. 



development, but not all the parts are readily 

 discerned in the adults due to ontogenetic fusion. 



The species did not differ in the anatomy of the 

 caudal complex, but they differed in the size at 

 which parts appeared and ossified. The 6.5 mm NL 

 C. equiselis was at the same stage of caudal 

 development as a 6.5 mm NL C. hippurus. From 

 7.6 to 16 mm SL, C. equiselis was more advanced. 

 Specimens >16 mm SL of both species had the 

 caudal complex equally ossified for the same 

 lengths, but epural, uroneural, and hypural fu- 

 sions occurred at shorter lengths in C. equiselis. 



Development of the caudal complex of C. hip- 

 purus is described here rather than C. equiselis 

 because small specimens were not available for 

 C. equiselis. Mostof the illustrations of the caudal 

 complex are of C. equiselis because they were 

 drawn before it was apparent that C. equiselis 

 < 7.6 mm were not available. Because both species 

 had identical caudal complex anatomy, no draw- 

 ings of C. hippurus' caudal complex were made for 

 specimens >7.6 mm SL. 



At 5 mm NL, C. hippurus had a straight 

 notochord. Hypurals 1 to 3, the parhypural, and 

 the haemal spine of the future preural centrum 2 

 were present in cartilage and 2+3 principal 

 caudal rays were counted (Figure 17). At 6 mm 

 NL, hypural 4 and an additional cartilaginous 

 haemal spine of the future preural centrum 3 were 

 present (Figure 18). Notochord flexion in C. hip- 



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