LOLIGO PEALII. 131 



vessels there is a small vessel that runs anteriorly over the ven- 

 tral surface of the heart and supplies the ink gland and rectum, 

 and another one that runs dorsally and posteriorly to supply part 

 of the reproductive system. 



(c) From the dorsal surface of the heart, near its anterior 

 end, a small vessel passes over the anterior and dorsal surfaces 

 of the stomach and finally passes into the gonad. 



The anterior aorta is larger than the posterior aorta. From 

 the anterior angle of the heart, which is to the right of the median 

 line, it follows a straight course alongside the esophagus to the 

 head. A number of small vessels are given off along its course, 

 and it is finally distributed to the head and arms. 



Draw the vessels connected with the systemic heart, into the 

 figure you have just made. 



Nervous System. The stellate ganglia may be seen through 

 the transparent lining of the mantle, on either side of the neck; 

 where the body joins the mantle. They send nerves to the man- 

 tle and ar joined to ganglia in the head (the infra-esophageal) 

 by connectives. Why does the mantle need such large, special 

 ganglia? Other small ganglia are situated in the body, but the 

 large and important ones are grouped in the head, where they are 

 supported and protected by cartilages. 



With a razor make a median sagittal section of the head of 

 a squid and notice: 



1. Dorsal to the esophagus a rounded mass, the supra-eso- 

 phageal ganglion, which is supposed to represent the fused cere- 

 bral ganglia. 



2. Ventral to the esophagus the elongated infra-esophageal 

 ganglion, which is supposed to represent the fused pedal and 

 visceral ganglia and (together with the masses that connect the 

 supra- and infra-esophageal ganglia around the esophagus) the 

 pleural ganglia. 



3. The anterior prolongation of the infra-esophageal gan- 

 glion to form the pro-pedal portion, which supplies nerves to the 

 arms. 



4. The small supra-buccal ganglia, lying dorsal to the esoph- 

 agus, and a little further anterior than the ends of the pro-pedal 



