616 REPTILIA. 
Some Peculiarities in the Organs of Chelonia 
In Chelonians and in all higher animals except serpents, there are 
twelve cranial*nerves, for, in addition to the usual ten, a spinal 
accessory to cervical muscles, and a hypoglossal to the tongue, are 
ranked as the eleventh and twelfth. 
The gullet of the turtle shows in great development what is hinted at 
in others, long horny papillae pointing downwards ; it is probable that 
these help to tear up the food (seaweed in the case of the turtle). 
<p irfee Wee 
GENS 
Fic. 333.—Internal view of the plastron of the 
Greek tortoise. 
EP., Epiplastron (clavicle?); ENT, entoplastron (inter- 
clavicle?); AYO., hyoplastron; H¥PO., hypo- 
plastron; X/P/H1J., xiphiplastron. 
The heart is three-chambered, but an incomplete septum divides the 
ventricle into « right portion, from which the pulmonary arteries and 
the left aortic arch arise, and a left portion, from which the right aortic 
arch issues. From the right aortic arch, which contains more pure 
blood than the left, the carotid and subclavian arteries are given off. 
ae left aortic arch gives off the cceliac artery before it unites with the 
right. 
The lungs are attached to the, dorsal wall of the thorax, and have 
only a ventral investment of peritoneum; each is divided into a series 
