FISHERY BULLETIN: VOL. 70, NO. 3 



22) and/or below (Figure 21). The oblique 

 mark adjacent to the genital region is obliter- 

 ated in some adults, but in others (Figure 23) 

 is very clearly delineated. 



GEOGRAPHICAL VARIATION 



Very young specimens of the Hawaiian spin- 

 ner (Figure 24, and Figure 7 in Perrin and Hun- 

 ter, 1972) were not available for examination 

 nor was it possible to determine with certitude 

 the degree of maturity of most of the animals 

 seen. One large male observed (PUKA at Sea- 

 life Park in Waimanalo, Oahu), however, has 

 been in captivity for 5 years and can be presumed 

 to be adult. The major differences between the 

 Hawaiian spinner and the whitebelly spinner of 

 the eastern Pacific are that in the Hawaiian ani- 

 mal the light ventrum extends dorsad nearly to 

 the level of the eye, as it does in its extreme ex- 

 pression in the whitebelly spinner, and is not 

 speckled at the margin. The dorsal fin becomes 

 increasingly erect with development, but is al- 

 ways at least slightly falcate, and the ventral keel 

 associated with triangular and canted fins in the 

 eastern Pacific spinners is all but absent. All 

 contrasts are on the average more pronounced: 

 between cape and lateral field, flipper band and 

 gular area, gape mark and underside of lower 

 jaw. The ventral margin of the cape follows a 



Figure 10. — Close view of genital re- 

 gion of adult male eastern spinner de- 

 picted in Figure 9. 



Figure 11. — Lateral (a) and ventral 

 (b) views of calf of whitebelly spin- 

 ner. Female, 105 cm, from 8°N, 

 109°45'W, March 5, 1969. Perrin field 

 no. PQll; U.S. National Museum 

 395601 (complete skeleton). Photo- 

 graphed frozen after approximately 

 1 month in frozen storage. 



Figure 12. — Subadult whitebelly spin- 

 ner. Female, 129 cm, from 9°47'N, 

 133°25'W, August 11, 1970. Perrin 

 field no. WFP58; U.S. National Mu- 

 seum 396036 (complete skeleton). Pho- 

 tographed after frozen for several 

 months and thawed in water. 



convex smooth curve over the eye in the white- 

 belly spinner but dips over the eye in the Ha- 

 waiian form. 



The differences among the whitebelly, eastern, 

 and Hawaiian spinners are summarized in Table 

 1. These differences appear to be based primar- 

 ily in differential development. The small sub- 

 adult of the whitebelly spinner (Figures 12 and 



Table 1. — Summary of some external features differing between adults of Hawaiian, whitebelly, and eastern 



spinner porpoise. 



990 



