the sexual phenotype of an individual. Width can be easily 

 measured under a dissecting microscope. After fixation, width in 

 the middle part of the gonads is less than 1.1 mm in phenotypic 

 females, whereas it is greater than 1.1 mm in phenotypic males. 

 Since the shape of gonads is not very regular, we recommend a 

 histological study if the width is between 1.0 and 1.2 mm. This 

 width is observed only in 6.6-7.5% of neonates. 



The length measurement of the gonad is not a good 

 determinate of sex phenotype, because it is between 9.0 and 12.5 

 mm when the temperature of egg incubation is between 28.75° C and 

 30.5°C. 



The method is only reliable for Dermochelvs coriacea and 

 cannot be applied to other marine turtle species, because the 

 ovaries are more differentiated than in Dermochelys coriacea and 

 are as wide or slightly wider than the testes. 



These data have been used to diagnose the sexual phenotype 

 of emerged neonates from 34 different nests on a beach in French 

 Guiana in 1981, 1983, 1984 and 1985. A total of 647 individuals, 

 8 to 4 per nest, has been studied. The sex-ratios in nests have 

 been interpreted as a function of the temperature of the sand, at 

 the same depth (60-80 cm) as the nests, during the periods that 

 are thermosensitive for sexual differentiation. In French 

 Guiana, the nesting period of marine turtles generally begins in 

 February and includes the rainy season (April to the beginning of 

 July) during which the sand temperature is lower than 29° C, and 

 the dry season (end of July to October) during which the sand 

 temperature is often higher than 30° C. Mature females of 

 Dermochelvs coriacea deposit 4 to 7 clutches of 50 to 148 eggs, 

 at 9 to 11 day intervals, during the nesting period. In earlier 

 nests, the hatchling sex-ratio is generally biased in favor of 

 males, whereas, in later nests it is biased in favor of females. 



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