SEA-FISHERIES LABORATORY. 4(,3 



The Arteries. (Pis. VIII, IX.) 



The following arteries are given off from the heart : 

 At the anterior end (1) the median Cephalic artery, and on 

 each side of this is (2) a Lateral artery, and (3) a Hepatic 

 artery, all passing forwards. At the posterior end there 

 are two median arteries arising ahont the same point, (4) 

 the Descending artery passing downwards, and (5) the 

 Posterior Aorta passing backwards above the intestine. 



At its origin from the heart each artery is valved, so 

 as to prevent the blood from returning. 



Cephalic artery [Ophthalmic artery] (PI. Till, fig. 

 51. o.art.). This is a median artery arising from the 

 anterior end of the heart. From its origin it passes 

 directly forward above that portion of the gonads situated 

 between the internal adductor muscles of the mandibles. 

 It pursues a straight course over the pyloric and cardiac 

 regions of the stomach and between the anterior gastric 

 muscles. So far the course of the artery has been entirely 

 superficial, but near the anterior end of the cardiac 

 fore-gut it dips downward and divides into two 

 branches immediately above the brain. Each branch 

 passes outward and supplies the eyes and also the various 

 parts of the front region of the head. 



Lateral artery [Antennary artery] (PI. VIII, Fig. 

 51. a.art.) There is one pair of lateral arteries, each of 

 which arises from the anterior end of the heart a little 

 outside of the origin of the cephalic artery. On leaving 

 the heart the lateral artery passes outward, making an 

 angle of about 40° with the cephalic artery. Almost 

 immediately it passes through the outer portion of the 

 internal adductor muscle of the mandible (i. a. ma 7 .). It 

 then curves outward, sweeping around the stomach until 

 it reaches the external abductor muscle of the mandible 

 (e. b. ma 1 .). Here it divides into two parts — (1) an outei? 

 cc 



