THALASSOCHELYS CORTICATA. 433 



belong to a different genus. The long list of synonyms will have to 

 be subdivided and referred each to its proper species. 



The shell of the Loggerhead Turtle is too thin to be of any use to 

 the arts. Its flesh is of a very inferior quality and unfit for the 

 table. The fat is transformed into oil, which is used in the arts. 



More than a century and a quarter ago, Labat, in his "Voyages 

 aux Isles de 1'Amerique," in speaking of the "Caouane," or Loggerhead 

 Turtle, states, that it grows to a larger size than either the "Green 

 Turtle," or the " Caret," of the same localities. 



DESCR. The specimen which lies before us, and from which the 

 accompanying figure was made, is a little over one foot in total length; 

 it is the only one brought home by the Expedition. The vertebral 

 protuberances are still quite prominent, whilst the lateral ones have 

 almost completely disappeared. The periphery of the carapax is 

 likewise still conspicuously serrated. The plastron itself exhibits 

 four interrupted ridges ; the two middle ones extending over the six 

 pairs of contiguous shields, forming a sort of stretched ellipsis, whilst 

 the two outer ones extend over the lateral shields, and are a good 

 deal shorter, and less conspicuous. The specimen represented in fig. 

 1, exhibits an anomaly in the anterior vertebral shield, which is irre- 

 gularly subdivided into two; the anterior division being the smaller 

 of the two, and more developed upon the left side, where it affects 

 the anterior middle marginal shield, which is quite reduced in width. 



The upper aspect of the head is subconvex ; its very surface is ren- 

 dered uneven by elevations and shallow grooves : the middle region of 

 most plates being somewhat raised, whilst their commissure is de- 

 pressed. The middle occipital plate (a) is the largest ; the anterior latero- 

 occipitals (bb), are next in size; then the anterior parietals (cc), the 

 postfrontals (dd), the postparietals (ee),the vertex plate (/), the 

 posterior latero-occipitals (g g), the prefrontals (7< h), the central post- 

 occipital (*'), the lateral postoccipitals (k k), and finally, the inter- 

 frontals (II), which are the smallest when subdivided; whilst, if 

 united into one, it would be subequal with the lateral postoccipitals. 



We dare say, the relative size of the cephalic plates may change 

 somewhat, according to the size of the specimen under examination, 

 especially the occipitals of various denominations ; still, we believe 

 they never do vary so much as to render their study unavailable for 

 zoological purposes. These plates are so accurately represented in 



109 



