ETJPAGURUS. 517 



The Arteries* (figs. 25, 26 and 27) leaving the heart 

 are for the most part easy to trace, but the dissection is 

 greatly facilitated if about a cubic centimetre of strong 

 borax-carmine or methyl-green solution in water be 

 introduced into the heart of the living animal by a 

 hypodermic syringe an hour before it is killed. It is 

 advisable to stupefy it with a weak solution of alcohol 

 before operating, and the hole in the carapace can be 

 conveniently stopped by a drop of hot wax. The stain 

 will be found to have attached itself to some extent to 

 the walls of the vessels, which are thus rendered visible 

 throughout their courses. Three main trunks run 

 forwards from the heart, the median cephalic (or 

 ophthalmic) artery, and the paired lateral (or antennary) 

 arteries (fig. 25, PL II). 



The Ophthalmic artery (opth. a., fig. 25) lies close to 

 the surface; it may be seen through the carapace in 

 injected specimens. Passing over the top of the stomach 

 without giving off any important branches, it plunges 

 down and divides into two vessels, one on either side of 

 the brain, which supply the region of the front of the 

 cephalon. The vessel is dilated into a flask-shaped bulb 

 just in front of the heart. 



The Lateral arteries (ant. a.) arise on either side of 

 the cephalic artery. While the median vessel rises on 

 leaving the heart in order to surmount the stomach, the 

 lateral arteries turn sharply outwards and pursuing a 

 level course on either side supply both that organ and the 

 surrounding tissues with branches. At their anterior 

 extremities the arteries bifurcate and give numerous 

 branches to the excretory organ and muscles which lie 

 laterally in the cephalon. 



* For a comparative study of Decapod arterial systems see :— 



Bouvier, Ann. des sci. nat., zool., Ser. 7, Vol. XI, 1891, p. 197. 



