GENERAL NOTES ON SNAKES.. 



609 



and thus the serpent flows onward. But this account of the 

 mechanism of movement does not suggest the swiftness or 

 the beauty of what Ruskin calls " one soundless, causeless 

 march of sequent rings, and spectral procession of spotted 

 dust, with dissolution in its fangs, dislocation in its coils." 



r.do. 



iv.c. 



d.d. 



l/i. 



/ do. 



FIG. 299. Heart and associated blood vessels of snake. 



c., Common carotid artery ; /., jugular vein ; v., vertebral artery ; 

 s.z'.c. , superior vena cava ; /.., pulmonary artery ; r.ao., right 

 aortic arch; i.c'.c., inferior vena cava; d.a., dorsal aorta; 

 p.v., pulmonary vein disappearing behind ventricle on its way 

 to left auricle ; Lao., left aortic arch ; d.B., ductus Botallii, an 

 embryonic vestige ; th., thyroid artery. 



" Startle it ; the winding stream will become a twisted 

 -the wave of poisoned life will lash through the 



arrow 



grass like a cast lance. 



One of the most distinctive characteristics of the skull is 

 the mobility of some of the bones. Many of the Ophidians 



39 



