518 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The Hepatic arteries (Jiep. a.) are given off from 

 the sides of the heart. They are small and have no 

 longer the important function which is assigned to them 

 in the Macrura and Brachyura, and their part in 

 supplying blood to the liver has been entirely taken over 

 by the superior abdominal vessel. They terminate in 

 small twigs on the gut. 



The Sternal artery (d. st. a. and st. a., figs. 26 and 28) 

 is the largest and most prominent vessel connected with 

 the blood supply. It arises in the median line at the 

 extreme postero-ventral corner of the heart just under- 

 neath the superior abdominal vessel, but while the latter 

 follows in the thorax the course of the gut, the former 

 immediately swings to the left and plunges downwards. 

 After passing the intestine, the sternal artery turns 

 forward sharply and runs horizontally from the seventh to 

 the fifth thoracic somites, when it again turns down and 

 pierces the central ganglionic mass between the nerves 

 of the second and third pairs of pereiopods. Under the 

 nerve chain the vessel divides into anterior and posterior 

 branches, running towards the head and tail respectively 

 (fig. 26). This portion of the vessel may be con- 

 veniently called the inferior thoracic portion of the 

 sternal artery. The anterior portion of this ventral artery 

 gives branches to the chelae and the mouth parts, and 

 two median branches ascend through the central gang- 

 lionic mass to supply the lower part of the stomach, the 

 caeca, and part of the renal organ. After the branches 

 to the first maxillipedes have been given off, the vessel 

 divides, the two branches pass to the front of the 

 oesophagus and anastomose on its walls, without, how- 

 ever, forming a ring. From each side branches to the 

 maxillae and mandibles arise. 



The posterior portion of the sternal artery is typical 



