FISHERY BULLETIN: VOL. 80, NO. 2 



37 specimens did not have a distal radial for the 

 anteriormost ray (Table 5). 



CAUDAL FIN 



Caudal fin rays first appeared at about the 

 same sizes as the dorsal and anal rays (Table 1). 

 The caudal fin rays developed in the caudal fin- 

 fold ventrad in preflexion larvae first on hypurals 

 2 and 3 and were added in an anterior and pos- 

 terior direction. After complete notochord 

 flexion between 6.3 and 8.0 mm ESL, the 

 secondary caudal rays developed dorsad and 

 ventrad in an anterior direction. Caudal rays 

 were first seen in a 5.4 mm ENL specimen and all 

 larvae longer than 6.1 mm ENL had some caudal 

 rays developing (Table 9). The full complement of 

 9+8 principal rays developed between 8.8 and 

 11.0 mm ESL. All Xiphias longer than 26.6 mm 

 ESL had the adult_count of (8-10)+9+8+(9- 

 ll)=34-38 (N = 15, X = 35.9, SD = 1.55) rays 

 (Tables 9, 10). The upper and lower caudal lobe 

 had equal numbers of rays or they differed by one 

 ray (Table 10). A procurrent spur (Johnson 1975) 

 was not oberved in Xiphias. 



CAUDAL FIN SUPPORTS 



The caudal fin rays were supported by some of 

 the bones of the hypural complex and only two 

 posteriormost centra (PU2 and urostyle) were in- 

 volved in the support (Fig. 17). The bones which 

 supported the fin rays directly or indirectly in 

 larvae and juveniles of Xiphias were two centra 

 (PU2 and urostyle), one specialized neural arch, 

 three epurals, one paired uroneural, five auto- 

 genous hypural bones, one autogenous par- 

 hypural, and one autogenous haemal spine. One 

 of 164 specimens examined had the unusual 

 count of 16+11=27 vertebrae and had two 

 autogenous haemal spines on preural centra 2 

 and 3. We were able to see all these supporting 

 bones during development (Figs. 18-23; Table 

 11), but in the adults some parts were ontogeneti- 

 cally fused. 



Between 3.7 and 6.2 mm ENL, Xiphias had a 

 straight notochord in the caudal area. Notochord 

 flexion was between 6.3 and 8.0 mm ENL. Before 

 notochord flexion hypurals 1-4, the parhypural 

 (Ph), and the haemal spine and arch (Hs) of the 

 future preural centrum 2 were developing 

 ventrad in cartilage (Fig. 18; Table 11). Dorsad 

 the neural arch (Ns) of the future preural cen- 

 trum 3, the specialized neural arch ("Na") of the 



Table 9.— Caudal fin ray development for 200 Xiphias gla- 

 dius (3.7 mm ENL-225, 668 mm ESL). SCR, secondary caudal 

 rays. PCR, principal caudal rays. X= mean, SE = standard 

 error of the mean. Specimens are undergoing notochord 

 flexion between dashed lines at 6.3-8.0 mm ENL. 



Table 10.— Adult caudal fin ray 

 counts for 15 Xiphias gladius (26.7- 

 225, 668 mm ESL). USCR = upper 

 secondary caudal rays, PCR = prin- 

 cipal caudal rays, LSCR = lower 

 secondary caudal rays. 



future preural centrum 2, and the three epurals 

 (Ep) were developing from cartilage (Fig. 19). 

 Appearance of the cartilaginous parts was from 

 anterior to posterior. After notochord flexion a 

 cartilaginous hypural 5 (Hy) and a bony uroneu- 

 ral (Un) developed between 9.8 and 12.5 mm 

 ESL (Figs. 20-21; Table 11). 



The parhypural and hypurals 1-5 developed 

 from separate pieces of cartilage. This is shown 

 for the parhypural and hypurals 1-2 in Figure 

 18. Joining of the proximal portions of the par- 

 hypural and hypurals 1-2 by cartilage starts 

 with the parhypural and hypural 1 between 5.4 

 and 5.6 mm ENL and extends to hypural 2 at 5.7 

 mm ENL. All specimens have the parhypural 

 and hypurals 1-2 joined proximally with carti- 

 lage at 6.9 mm ENL or ESL as shown in Figures 

 19 and 20. Hypurals 3-5 are never joined by carti- 

 lage during development (Figs. 19-21). The car- 

 tilaginous proximal joint is lost during develop- 

 ment when the hypurals are fully ossified 

 between 27 and 34 mm ESL (Fig. 22). 



Ossification of the cartilage bone in the caudal 

 complex of Xiphias started with the preural 



172 



