1897J MICROSCOPICAL JOURNAL; 15 



many df the vessels can be found. A single pair of 

 aortic arches pass dorsally from the bulb ajid meet, as iu 

 the iish, to form the dorsal aorta which then runs down 

 the body cavity in its dorsal wall and beyond, into the 

 post abdomen. Partial additional arches can be tract l 

 (in the frog) which lead out from the bulbus to the head 

 carotids and to the lungs pulmonary arteries^ sub-clavians 

 pass from the dorsal aorta into the arms; in the trunk 

 region there are coeliac, mesenteric q.\\(\. still more po.ste^- 

 iorly rf«(a:/ arteries; at the level of the hind limbs thej-e 

 are iliac arteries going into them from the dorsal aorta; 

 there is an artery running in the skin ctitaneous, it arises, 

 from the subclavian and also from the iliac. Veins from 

 the kidneys renal veins coml ine to form a vessel the post- 

 caval vein (posterior vena cava) which runs close below 

 the back-bone directly forward and into the hinder side 

 of the right auricle. It receives vessels from the liver, 

 hepatic vein, but none from the stomach or intesiiries. 

 The blood from the iliac system, and muscles and skin of 

 the post-abdomen is collected into a vessel of importance 

 in the amphibia but of minor significance in the higher 

 vertebrates, the «?//m(?r abdominal vein', it runs in the 

 mid-ventral line closely related to the skin there, and 

 enters the hinder side of the liver where its capillaries 

 anastomose with those from the portal vein. The blood 

 from the anterior parts of the body returns to the heart 

 through jugular and sub-clavian veins, which contribute ttt 

 form the pre-caval vein, entering the riglit jiuricle. 

 Thus all the systemic blood is returned to the right 

 auricle. The blood from the lungs, is returned to the 

 left auricle by pulmonary vnns.l 



7. The Alimentary Viscera. — The liver is the most 

 noticeable organ of the system; it lies in the mid-ventral, 

 line directly behind the heart, and reaches back more 

 than half way down the body cavity. On its posterior 



