202 



THE ANATOMY OF VEETEBBATED ANIMALS. 



In tlie Turtle the plastron consists of nine pieces — one 

 median and anterior, four lateral and paired (Fig. 64). These 

 pieces may be named — the median, entoplastron ; the first t 

 lateral, epiplastron ; the second, hyoplastron ; the third, Injpo- 

 plastroyi; and the foui-th, xiphipladron* The entoplastron i 

 and the two epiplastra con-espond with the median and! 

 latei-al thoracic plates of the Labyrinthodont Amphibia, . 



Fig. 64. 



Fig. 64.— The plastron of the Green Turtle {Chehne midas):—I.d, 

 interclavicle ; cl, clavicles ; Hy.p., hyoplastron ; Hp.p, hypoplas- 

 tron ; Xp, xiphiplastron. 



and very probably answer to the interclavicle and clavicles 

 of other Vertebrata. 



The sacrum consists of two vertebrae. The expanded 

 sacral ribs are not ankylosed with the centra and arches 

 of their vertebrae. 



The tail is flexible, and consists of proccelous vei-tebrae. 

 The anterior caudal vertebrae have no transverse processes, 



* Believing the plastron to 

 answer to the sternum of other 

 Vertebrata, anatomists have 

 termed these elements of the 



plastron entosternujn, epistemum, 

 hyontertium, hypoeiernum, and 

 xiphistemum. 



