I've had a good look at the books and enlarged the photo and I'm confident that this is a Hawksbill Turtle. Reasons being, the beak projects forward in Hawksbills, whereas it doesn't in Greens; there apprears to be an indication of two pairs of prefrontals further suggesting Hawksbill, whereas Greens only have one pair of prefrontal scales; there are only five, relatively large temporal scales on this specimen, as opposed to the more numerous, smaller temporal scales present on Greens.
The temporal scales are located on the side of the head between the parietal scales and the supralabials, and behind the postocular scales. However I use the term more loosely in this case and include all the scales behind the eye (including the postoculars) as there's so few scales in the temporal region in this species. Basically, there's relatively fewer scales in the temporal region in Hawksbills than in Greens. The barnacles tend to gather in the sutures between the scales and between the scutes, making them more visible, particularly on the marginal scutes in this photo.