POTTHOFF; DEVELOPMENT AND STRUCTURE OF FINS IN CORYPHAENA 



tween 18 and 24 mm SL and for C. equiselis 

 between 13 and 18 mm SL (Figure 1). Gibbs and 

 Collette (1959) reported 46-65 {x = 58.4) dorsal fin 

 rays for C. hippurus and 48-60 i'x = 52.6) for 

 C. equiselis. My counts and those of Gibbs and 

 Collette (1959) differ because Gibbs and Collette 

 included counts of small specimens (from about 12 

 mm SL) of both species in their sample and 

 because C equiselis develops a full complement of 

 dorsal fin rays at a smaller size than C hippurus 

 (13-17 mm SL vs. 18-23 mm SL); therefore, more 

 C. hippurus than C equiselis with incomplete 

 dorsal fins were counted by Gibbs and Collette, 

 and inclusion of incomplete dorsal fin ray counts 

 widened the range of counts and lowered the mean 

 number of dorsal fin rays. Dorsal fin ray counts 

 reported by Shcherbachev (1973) (46-67 for C. 

 hippurus and 48-60 for C equiselis ) are from his 

 ov^m data and those of Gibbs and Collette. Roth- 

 schild (1964) reported 54-58 {x = 57.9) for adult 



C. equiselis, all from the Pacific Ocean. Here, 

 count differences probably resulted from the 

 method of counting (cleared and stained vs. 

 preserved material) but may also have been due 

 to population differences. 



Dorsal fin rays were first seen in C hippurus at 

 6 mm SL and were present in all specimens at 

 8 mm SL (Figure 1). The smallest specimen of 

 C. equiselis (6.5 mm SL) already had 12 dorsal fin 

 rays. Development of the dorsal fin rays for both 

 species started in the dorsal finfold at the posterior 

 third of the body (Figure 2). This was above the 

 22d-24th myomere for three C. hippurus with 

 only 3 or 4 dorsal fin rays. With growth, addition of 

 dorsal fin rays was in an anterior and posterior 

 direction for both species, but more fin rays were 

 added anteriorly (Figure 2). The dorsal fin, despite 

 the more rapid addition of rays anteriorly, reached 

 completion posteriorly at a smaller size of the 

 larvae than anteriorly. This is because more 



70 



60 



t/i 



50 



■40 



CO 



U.30 



20 



10 



5 S 



99 



5 8 3 6 



V^. 



5 I 



'M'W'* 



5 0.. 



C. equiselis^ 

 C. hippurus i 



5 6 7 8 



9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 >23 

 LENGTH, mm NL or SL 



Figure l. — Number of dorsal fin rays in relation to length in 161 Coryphaena equiselis (6.5-230 mm NL or SL) and 211 C. hippurus 

 (5.0-172 mm NL or SL). Range (vertical line), mean (horizontal line), and 2 standard errors about the mean (white and black 

 bars) are indicated. Number of specimens for each length interval is given above the range and is in italics for C. equiselis. 



279 



