348 REPT1LIA. 



the parts where the nerves go out 1 . At the basis of the skull it is 

 attached to a cartilaginous knob 2 . Along the top of the skull it has 

 different attachments, which would appear to answer the purpose of a 

 falx; and between the cerebrum and cerebellum, there is either the 

 going out or the coming in of the longitudinal sinus. There are eleven 

 pairs of nerves arising from the brain: the ninth pair receives the 

 accessorius 3 . 



Of the Breathing of the Turtle. — It appears to be a considerable effort 

 in a turtle to draw in its breath, as they have no distinct thorax or 

 apparatus for breathing. It becomes a distension of the whole body, 

 which includes the abdomen. If a turtle is thrown upon its back, and 

 makes an inspiration, we may observe that his four fins are, as it were, 

 erected : the breast-bone is pushed forwards, and they swell out where- 

 ever the parts are soft ; all this is done, I conceive, by the muscles of 

 the extremities moving their respective bones in an inverted order ; for, 

 instead of their moving the extremity, the extremity becomes the fixed 

 point ; and the bones answering to the clavicles are moved forwards ; 

 and the bones of the pelvis at the lower part are pushed against the 

 inside of the breast-bone, so that the whole bone [plastron] is pushed 

 out *. They appear to draw in their breath but once in twenty minutes 

 or half an hour, and often at a much longer interval. They are con- 

 stantly working their throat, moving it outwards and inwards, which 

 made me suppose that this motion was short breathing ; but their doing 

 the same when under water, when no air could pass or enter, made me 

 relinquish that idea. When its throat was cut, and bleeding freely, I 

 could hardly observe that the blood flowed by jerks. 



Of the Arteries. — The heart has three arteries arising from it, viz. a 

 right, middle, and left. The right supplies every part of the body 

 excepting the lungs, liver and intestinal canal ; the middle supplies the 

 liver, stomach, and guts ; and the left supplies the lungs only. 



i [Hunt. Preps. Phys. Series, Nos. 1312—1314.] 



2 [The ligamentum denticulatum arises from this knob, from which it diverges on 

 each side to gain its usual situation between the anterior and posterior roots of the 

 spinal nerves. The fourth ventricle is closed posteriorly by a diaphanous layer of pia 

 mater. The cellular nocculent external surface of the arachnoid sac is turned towards 

 the brain ; it does not penetrate the ventricles.] 



3 [The homologue of the ninth, or hypoglossal, nerve in man, arises two lines mesiad 

 of the nerve which the accessorius joins ; the nerve which, on account of the separate 

 origin of the glossopharyngeal, is the ninth in number in the turtle, is the nervus vagus. 

 The nervus accessorius comes from the posterior myclonal tract, as low down as the 

 third cervical nerve.] 



4 [Such a movement is only possible in the turtles and trionyces ; in the rest of 

 the chelonian order the plastron is fixed by bone to the carapace.] 



