POTTHOFF and KELLEY: OSTEOLOGICAL DEVELOPMENT IN SWORDFISH 



Figure 7.— Threee possible shapes of anteriormost 

 dorsal and anal pterygiophores for 37 Xiphias gladius 

 14.7-668 mm ESL and the number of fin rays associated 

 with each pterygiophore shape. 



025mm 



mens, no rays were associated with the anterior 

 most pterygiophore. The posteriormost dorsal 

 fin ray was double and was serially associated 

 with the posteriormost pterygiophore (Figs. 9, 

 10). The double ray lacked a secondary associa- 

 tion, but a stay was present under the double ray 

 (Figs. 9, 10). Middle radials were absent in 

 Xiphias. Total dorsal pterygiophore count was 

 either equal to or one to two less than the dorsal 

 fin ray count, depending on the number of rays 

 associated with the anteriormost pterygiophore. 

 In larvae, juveniles, and small adults of 

 Xiphias the dorsal proximal radials inserted in 

 the interneural spaces. In 39 juveniles and small 

 adults with fully formed fins, the first inter- 

 neural space (bounded by head and first neural 

 spine) lacked inserting pterygiophores or pre- 

 dorsal bones. The second interneural space 

 (bounded by first and second neural spines) had 

 four to seven {X- 5.2), the third space had three 

 tofive (X - 4.2), the fourth space had two to three 

 (X = 2.9), the fifth space had two to three (X= 2.4), 

 and the remainder of the interneural spaces had 

 one to three pterygiophores, but usually two 



Figure 8.— Left lateral view of the two anteriormost 

 dorsal fin pterygiophores with their associated rays 

 in the second interneural space for various sizes of 

 Xiphias gladius. Starting from left the specimens' 

 lengths in millimeters ESL are: top row, 15.9, 20.4; 

 middle row, 26.7, 33.6; bottom row, 52.4, 225. D, 

 distal radial; NPr. neural prezygapophysis; Ns, 

 neural spine; P, proximal radial; R, fin ray. Carti- 

 lage, white; ossifying, stippled. 



(Fig. 11). Usually the posteriormost dorsal 

 pterygiophore inserted in the 22d interneural 

 space and occasionally in the 21st (Fig. 11; 

 Tables 6, 7). 



In Xiphias, dorsal fin pterygiophores first 

 appeared in cartilage before the fin rays at 4.8 

 mm ENL, but not until 6.0 mm ENL did all 

 specimens have cartilaginous pterygiophores. 

 Two Xiphias, 5.1 and 5.6 mm ENL, lacked 

 dorsal pterygiophores but had some cartilagi- 

 nous anal pterygiophores. Dorsal pterygiophores 

 were first seen at the center of the body between 

 the 11th and 18th interneural spaces (Fig. 6; 



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