Table l.-Results of microscopic examination of pigment distribution in skin of two 

 Deiphinus delphis. Codes explained in text. 



Table 2.-Average pigment density values for four major fea- 

 tures of the color pattern of Deiphinus delphis. Coded values in 

 Table 1 are averaged over bases, edges, and bands, over all 

 relevant samples, and over both animals. Number of samples 

 included for each animal is in parentheses. 



Discussion 



The color pattern of Deiphinus evidently con- 

 sists of two overlapping and interacting pigmen- 

 tation components that differ mainly in the den- 

 sity and size of pigment particles. The pigment 

 exhibits a continuum of grain size, with the very 

 smallest particles being associated with a buff 

 color. It seems likely that the diffuse pigment is 

 also composed of particles too small for resolution 

 with the light microscope. This evidence suggests 



that there may be a developmental progression in 

 grain size from the unpigmented or truly white 

 condition through buff and gray to black. This 

 result is consistent with Mitchell's (1970) proposal 

 of the "saddled" pattern as most primitive in 

 recent cetaceans. Inhibition of pigment aggrega- 

 tion could result in the high concentration of dif- 

 fuse pigment which is typical of buff regions in 

 Deiphinus. Fox (1953) and others have stated that 

 there are different types of melanins, possibly 

 characterized by different chemical compositions 

 or structures, although none have been adequately 

 described chemically, due to their insolubility and 

 their general lack of adaptability to most physico- 

 chemical methods. From the previously described 

 evidence it may be suggested that the type of 

 malanin which produces the buff color is of a com- 

 position which does not allow its further 

 polymerization, but may well favor its combina- 

 tion with a protein, as phaeomelanin, instead of 

 aggregation into granules. One might also 

 hypothesize control by dispersing or concentrating 



443 



