782 



PERISTOMIAL HAEMOCOEL : SYSTEMIC AORTA ; CEPHALIC ARTERIES. 



right and left lobes of the liver, and, after a further course of about 15 mm. (in the 

 adult) sends off two important arteries, the hepatic artery on the left and the gastric 

 artery on the right of the main aortic trunk. It then turns definitely forwards dorsad 

 of the crop, giving off other branches (Text-fig. 8) until it reaches the intercoelic 

 diaphragm which separates the peristomial from the peri-oesophageal haemocoel on the 

 dorsal side. Having arrived at this level, the dorsal aorta divides into the two main 



-La. 



s.m.a 

 -s.r. 



-b.a. 



--i.m.a. 



--n.m. 



-.a.c.a. 



-a.b.a. 



--/ 

 . _ m.c. 



-X.e. 

 .-pM.a. 



Fig. 9. N. pompilius, 3 . Dissection, from above, of the cephalic region to show the cephalic arteries. An 

 incision has been made through the nuchal membrane, the hood, and the buccal membrane. The brain- 

 capsule has been opened, and the median portion of the mantle behind the nuchal region has been 

 removed, b.c. buccal cone ; tent. int. extrabuccal tentacles (the external labial processes of Owen) ; l.a. labial 

 arteries supplying the buccal membrane and fringe; s.m.a. superior mandibular artery; s.r. superior retractor 

 muscles of the jaws (Owen) ; b.a. buccal artery ; i.m.a. paired inferior mandibular arteries ; n.m. nuchal 

 membrane ; a.c.a. anterior columellar artery ; a.p.a. anterior proveutricular artery ; f. ala infundibuli ; 

 m.c. free mantle-edge; c.e. cut edge of mantle; p.n.a. pallio-nuchal artery; d.a. dorsal aorta; cer. brain 

 with cerebral arteries ; h. cut edge of hood. 



N.B. — Apart from the cerebral arteries, all the anteriorly directed branches of the innominate arteries pass 

 below the cerebral capsule. [From Quart. J. Micr. Sci. Vol. 39, 1896.] 



cephalic arteries which I have formerly called innominate arteries. These are the feeders 

 of the peristomial haemocoel. 



