POTTHOFF: DEVELOPMENT AND STRUCTURE OF FINS IN CORYPHAENA 



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Figure 30. — Lateral external view of left side of pectoral girdle from a 47.6 mm SL Coryphaena hippurus (left) and a 48 mm SL 

 C equiselis (right). For explanation of sjrmbols, see Figure 29. Stippled, cartilage; darkened, bone. 



of the two cleithra and coracoids (Figure 25). No 

 fleshy interpelvic processes were present between 

 the bases of the fins. 



The basipterygium is a complex bone. For con- 

 venience of description, it was divided into three 

 parts which corresponded to the ontogeny of the 

 bone: the central part, which was the original 

 cartilage, the wings (Kishinouye 1923) of mem- 

 branous bone origin, and the two xiphoid processes 

 (de Sylva 1955), of which the posterior process was 

 of cartilage origin and the anterior process of bone 



origin. The central part of the basipterygium 

 carried the four wings along its length (Figures 

 31-33). Anteriorly the central part was tipped by a 

 small piece of cartilage. Posteriorly the central 

 part served the articulation of the fin rays. A thin 

 layer of articular cartilage was present in adults 

 on the posteriormost portion of the central part 

 (Figures 31, 32). Each basipterygium had four 

 wings, reminiscent of the two sagittal and two 

 lateral keels of pterygiophores. The wings formed 

 a dorsal and a ventral "V" shaped groove, and a 



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