34 CHELONIA CARETTA. 



short lateral angles, connected with the adjoining lateral plates; the fourth 

 vertebral is also hexagonal, but shorter, and with lateral angles more extended; 

 the fifth vertebral plate is pentagonal, slightly concave in front, with extensive 

 lateral margins and four articulating facets below. In the old animal all these 

 plates are nearly on an horizontal plane; the first being but very little curved 

 downwards in front, and the fifth as little behind. The lateral plates are five in 

 number, the first is smallest, with regularly triangular margins, and its basis 

 directed forwards and downwards; the second is irregularly quadrilateral, rounded 

 below and in front; the third and fourth are pentagonal, with two short borders 

 above, meeting at an obtuse angle; the fifth lateral plate is irregularly quadri- 

 lateral, broader below, or it has its posterior and inferior angle truncated where 

 it joins the eleventh marginal, which gives it a pentagonal form. 



Of the twenty-five marginal plates, the intermediate, or nuchal, is short in the 

 longitudinal, and more than three times as large in the transverse direction; it is 

 small in the middle, slightly concave behind, and much more so in front, and large 

 at its lateral extremities, each having two articulating surfaces, an upper smaller, 

 to join Avith the first lateral, and a lower larger, to unite with the first marginal 

 plate. The anterior marginal is irregularly quadrilateral and arched outwards; 

 the second is also quadrilateral, but concave in front; this and part of the fourth 

 making a border arched inwards over the anterior extremities; the third is irregu- 

 larly quadrilateral, smaller above, larger below^; the remaining marginal plates to 

 the eleventh included, are quadrilateral, and make an entire border, sometimes 

 waving, between the tenth and eleventh; the twelfth or supra-caudal plates are 

 sub-rhomboidal, and have a deep crescentic notch between them at their posterior 

 margin. 



The sternum is very full and rounded in front, smaller, but rounded behind. 

 The gular plates are large equilateral triangles, with their outer border rounded; 

 the brachial are regularly pentagonal, and so are the thoracic plates, but elon- 

 gated; the abdominal are broad and pentagonal; the femoral are also pentagonal, 

 but very irregularly so, having their posterior and external border concave; the 



