[Illustration: _Photo by York & Son_] [_Notting Hill._
The two white points visible on the lower jaw represent the pair of worm-like appendages which the creature uses as a bait to attract or capture fish.]
Of the typical Marine Turtles three distinctly characterised species are recognised by zoologists. These are the GREEN TURTLE, indispensable for soup at aldermanic banquets; the HAWKSBILL, or tortoiseshell-producing turtle; and the LOGGERHEAD. Of these three, the green turtle and the loggerhead more nearly resemble one another, and are apt to be confounded by the uninitiated. Such an error is very readily detected when the Chelonian comes to the table, the flesh of the loggerhead being rank and utterly unfit for food. In order, however, to be wise before the event, and to avoid a grievous misdirection of culinary energy--turtle being a standard dish in the coral seas--it is only necessary to count the number of large shield-like plates that flank each side of the central series in the creature's carapace. In the true green or edible turtle there are only four pairs of these large lateral shields, while in the loggerhead there are never less than five, and sometimes more. The loggerhead-turtle also, as its name implies, has a conspicuously larger and coarser head than the esculent species. The fact that while the green turtle is a strict vegetarian, feeding entirely on seaweeds, the loggerhead is altogether carnivorous, readily accounts for the diametrically diverse gastronomic properties of these two Chelonians. Both species attain to a considerable size, over 3 feet in length (the loggerhead being the larger), and are found inhabiting the same waters throughout the tropics.
The HAWKSBILL, or true tortoiseshell-producing turtle, never attains to quite as large dimensions as the two preceding species, though its carapace may measure as much as 2 feet 6 or 8 inches long. The structural feature that at once distinguishes the hawksbill from either the green or loggerhead species is the character of the horny shields developed on the surface of the carapace. Instead of the edges meeting in juxtaposition, as in those two forms, they overlap one another, like the scales of a fish, and are notable for their thickness and their exceedingly beautiful but variably marbled patterns. It is these marbled horny plates which constitute the tortoise-shell of commerce. In young individuals the substance is thin and very transparent, but thickens with advancing age, until in old individuals the plates may vary from 1/8 to ¼ inch in thickness. Like the two preceding species, the hawksbill, within tropical seas, enjoys a cosmopolitan distribution. Its habits, like the loggerhead's, are essentially carnivorous; but while the flesh is coarse and rank, the eggs are valued for the table.