ORGANS OF CHELONIA. 



565 



Some Peculiarities in the Organs of Chelonia. 



The brain of the adult shows a slight curvature 

 in all higher animals ex- 

 cept serpents, there aie 

 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 develop- 

 ment what is hinted at in 

 others, long horny papillse 

 pointing downwards ; it is 

 probable that these help 

 to tear up the food (sea- 

 weed in the case of the 

 turtle). There are usually 

 blind pockets or anal 

 bursse connected with the 

 cloaca. 



The heart is three-cham- 

 bered, but an incomplete 

 septum divides the ven- 

 tricle into a right portion, 

 from which the pulmonary 

 arteries and the left aortic 

 arch arise, and a left por- 

 tion, from which the right 

 aortic arch issues. From 



In Chelonians and 



Fig. 243. — Internal view of skeleton of turtle. 



• — From Edinburgh Museum of Science and 



Art. 

 H., Humerus; Sc, scapula, running dorsally ; c, 



coracoid ; e.c. epicoracoid ; p.c.-, precoracoid ; 



P., pubis; 1/., ilium, running dorsally; Is., 



ischium ; J*., femur. 



the right aortic arch, which contains 

 more pure blood than the left, the 

 carotid and subclavian arteries are 

 given off. The left aortic arch gives 

 off the cceliac artery before it unites 

 with the right. 



Unlike other Reptiles, the Chelon- 

 ians are said to have no renal-portal 

 system. 



The lungs are attached to the 



dorsal wall of the thorax, and have 



only a ventral investment of peri- 

 Fig. 244.-Dissection of Cheloman toneum each is div ; ded int0 a series 



heart.-After Huxley. of compartments into which branches 



r.v., Right half of ventricle; S., f the bronchus open. There is a 



septum ; t.v.. left half of ventricle ; t- , ,. w „„„„i„„. n j;„„i,..„„ m » 



*■.£., right aiiicle ;/.«., left auricle! slight muscular diaphragm. 



l.ao., left aortic arch; r.ao., right In the males, the kidney, the epi- 



aortic arch; p.a.., pulmonary arch, didymis, and the testes lie adjacent 



