1897J MICROSCOPICAL JOURNAL. 15 



many of tlie vessels can he found. A single pair of 

 aortic arches pass dorsally from the bulb and meet, as iii 

 the fish, 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 traci I 

 (in the frog) wriich lead out from the bulbus to the hf^ad 

 carotids and to the luiigs pulmonary arteries^ siib-clavians 

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

 region there are cotiiac, mesenteric aw^ still more postf''-- 

 iorly /r/m/ arteries; at the b^vel of the hind limbs theie 

 are iliac arteries going into them from the dorsal aort;i; 

 there is an artery running in the skin cutaneous^ 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 intestines. 

 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 anterior 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 cnpillaries 

 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 to 

 form the pre-caval vein^ entering the right auricle. 

 Thus all the systemic blood is returned to the right 

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

 left auricle by pulmonary veins.] 



7. The Alimentary Viscera. — The. liver \8 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 



