OF THE UNITED STATES 151 



years have designated these dermal scutes by certain names. 

 Those of the median row are termed vertebrals (v) ; the lateral 

 rows are the costals (co) ; while the ones round the border are 

 called the marginals (m). On the plastron, the dermal scutes are 

 known as the gulars (Fig. 41) ; the postgulars (pg) ; the pectorals 

 (p) ; the abdominals '(ab) ; the prseanals (pa) ; and the anals 

 (an). These scutes may be easily removed by the application of 

 heat, or steam, or boiling, and then the white bones of the true 

 carapace and plastron are exposed to our view for study. In the 

 figures these are defined by the dotted lines, and are termed the 

 costals (co) ; the neurals (ne) ; the nuchal (nu) ; the pygal (py) ; 

 the marginals (m) ; the entoplastron (ent) ; the epiplastron (ep) ; 

 the hyoplastron (liyo)', the hypoplastron (hyp), and the xyphi- 

 plastron (xyp). 



Young naturalists will have no trouble in acquiring these 

 names, and they are of no little importance in the study of che- 

 lonians. In classification the arrangement of the bones and the 

 dermal scutes is very convenient for the designation of species. 

 To appreciate this fact, I would advise the student to secure in 

 the market or elsewhere a small turtle of any species, and make 

 out for himself the structures to which I have just invited atten- 

 tion. 



In the big marine turtles found in different parts of the world, 

 the same general arrangement of the scutes will be found to hold 

 good. At the present writing I have at hand the carapace of a 

 young Hawk's-bill turtle (Caretta imbricata), and of it I made the 

 sketch shown in Fig. 42. This is the upper view, and the let- 

 tering is the same as Fig. 40. The vertebrals and costals in 

 Caretta always together number thirteen, and they are at once 

 recognized by their peculiar imbrication, hence the specific name 

 this species has received. The marginals form a serrated border 

 to its carapace, as shown in the cut (m). It is the Hawk's-bill tur- 

 tle that furnishes the famous tortoise-shell of commerce, and 

 owing to the demand for this, the animal is gradually being ex- 

 terminated. The scutes are removed by suspending the living 

 turtles over the fire until they start free from the carapace; they 

 are then detached and the tortured turtle allowed to return to 

 the sea. In this partly baked condition some doubtless survive, 

 but many must die ; but the only interest that this has for men is 

 the fact that the scutes are probably never reproduced so as to 

 even be fit for anything, or to be toasted off a second time. Chi- 



