20 



artery [fac. art.), which supplies the mandibles and the 

 lateral regions of the face. Neither the injections nor the 

 serial sections showed any oesophageal ring of the nature 

 described by Delage. Several small arteries are given off 

 from the posterior border of the antenno-facial arteries 

 which supply the oesophagus {oes. art.) and neighbouring 

 soft parts, as will be seen from the figure. The fact that 

 in many cases these small arteries dilate to an exaggerated 

 extent when injected, may account for the mistake. 



The lateral arteries (PI. III., fig. 1, lat. art.) run 

 forward and outward from the anterior end of the 

 heart, and in the first thoracic segment each anasto- 

 moses with the transverse artery from the dorsal 

 aorta. On the external side of each lateral 



artery, four thoracic arteries arise (i., ii., iii., iv.j, 

 supplying the first, second, third and fourth thoracic 

 segments. On the internal side of the thoracic artery a 

 number of branches are given off which ramify on the 

 walls of the gut {^int. art.) and hepatic tubules [hep. art.). 

 Close to the origin of the fourth thoracic artery a large 

 branch {f/en. art.) is given off, which supplies the terminal 

 portion of the vas deferens. A number of arteries arise 

 from the dorsal side of each lateral artery, and ramify 

 in the hypodermal tissues. 



The thoracic arteries (i., ii., iii., iv., v., vi., vii.). — The 

 course of each of the thoracic arteries, with the exception 

 of the sixth and seventh, is somewhat the same. Each 

 runs directly outwards, and, when dorsal to the hepatic 

 tubules, gives oft' a ventral branch which supplies these. 

 Following the curvature of the dorsal surface the arteiy 

 curves ventralh' ; a small artery arises which runs into 

 the dorsal longitudinal muscles. When it reaches the 

 insertion of the limb it bifurcates, the inner branch runs 

 inwards and supplies the ventral surface, the outer branch 



