FISHERY BULLETIN: VOL. 70, NO. 3 



parts of the world is emphasized in many indi- 

 viduals by a zone of lighter pigmentation (see 

 Figures 4 and 6 in Perrin, 1970b; Figure 1 in 

 Best, 1969; and Figure 3 in Nishiwaki, Naka- 

 jima, and Kamiya, 1965), which supports the 

 idea of separate origin of the two marks. In the 

 spotted porpoises, the combined pattern systems 

 are overlaid with discrete dorsal and ventral spot 

 systems that to greater or lesser extent obliterate 

 them (Perrin, 1970b). 



In Delphinus spp. (Figure 27, middle) the 

 dorsal field overlay is less extensive anteriorly 

 than the cape, resulting in invasion of the cape 

 by the ventral field and yielding a four-part criss- 

 cross pattern with zones of black, buflF, gray, and 

 white. The deduction to be made is that the 

 whitebelly region represents total lack of pig- 

 ment, the buff "thoracic patch" (terminology of 

 Mitchell, 1970) represents the color yielded by 

 the pigment of the cape alone, the gray "flank 

 patch" (of Mitchell) that of the pigment of the 

 dorsal field overlay alone, and the black dorsal- 

 most area that of the combined eflfect of the pig- 

 ments of the cape and the dorsal field overlay. 

 Chromatographic analysis of pigments present 

 in the various regions and comparison of the re- 

 sults with those of similar tests for other del- 

 phinids would contribute to verification or re- 

 jection of the suggested homologies. 



The pattern of Tursiops truncatus (Figure 27, 

 bottom) is very close to that of the spinners in 

 every respect, with the flipper band running to 

 the eye and demarcated dorsally by a narrow 

 light line. The dorsal field overlay of varying 

 darkness extends ventrad to about the same de- 

 gree as in the eastern spinner. Observation of 

 wild bottlenose porpoise in the eastern temper- 

 ate and tropical Pacific and examination of some 

 of the thousands of published photographs of 

 animals from around the world lead me to believe 

 that the main component of geographical var- 

 iation, as for the spinner porpoises, is the extent 

 and darkness of the dorsal overlay. In Ha- 

 waiian Tursiops that I have observed, the vent- 

 ral margin was high and sharply defined exactly 

 as in the Hawaiian spinner. 



The general cape system common to the four 

 forms discussed above corresponds roughly to 

 the "saddled pattern" described by Mitchell 



Figure 15. — Lateral (a) and ventral 

 (b) views of subadult whitebelly spin- 

 ner. Male, 166 cm, from 10°N, 129° 

 or 136°W, August 10-12, 1970. Perrin 

 field no. WFP71; U.S. National Mu- 

 seum 396023 (complete skeleton). Pho- 

 tographed after frozen for several 

 months and thawed in water. 



Figure 16. — Lateral (a) and ventral 

 (b) views of adult whitebelly spinner. 

 Male, 169 cm, from 9°47'N, 133°25'W, 

 August 11, 1970. Perrin field no. 

 WFP53; U.S. National Museum 

 896031 (complete skeleton). Photo- 

 graphed after frozen for several 

 months and thawed in water. 



Figure 17. — Adult whitebelly spinner. 

 Male, 174 cm, from 9°47'N, 133°25'W, 

 August 11, 1970. Perrin field no. 

 WFP76; U.S. National Museum 

 396170 (complete skeleton). Photo- 

 graphed after frozen for several 

 months and thawed in water. 



(1970) as a generalized and probably primitive 

 pattern within the Delphinidae. The "saddled 

 pattern" depicted in his Figure 7, however, is 

 definitely not that of the spinner porpoises, which 

 he included in a group of "saddled" species in 

 his Figure 17. I concur with Mitchell in his se- 

 lection of the "saddled" condition as a good can- 

 didate for a primitive pattern, insofar as his 

 definition of that pattern category pertains to the 

 "general cape system" described here. Lines of 

 evidence presented here leading to this conclu- 

 sion are the possession in common of a relatively 

 invariant cape system by several delphinid spe- 

 cies and the tendency of the cape to be partially 

 marked, distorted, or obliterated in a varying 

 fashion within a species or species group not so 

 much by alteration of its intrinsic form but 

 more by interaction with more plastic overlying 

 systems or (as Mitchell pointed out in the case 

 of the "spinal blaze") by subtraction through 

 invasion by areas of nonpigmentation. 



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