Introduction to Animal Morphology. 245 



are called pedal ganglia. Two long (sympathetic ?) 

 nerves, arising from the^cesophageal ganglion, may 

 unite posteriorly to form a parieto-splanchic or anal 

 ganglion. Sense-organs may exist as tentacles, 

 ciliated smell organs, eyes, otocyst, &c. 



The digestive canal never communicates with the 

 body cavity, and is more or less looped, so that the 

 anus is often near the mouth, and always near the 

 breathing cavity. The intestine is sometimes attached 

 to one or more rudimental transverse partitions, 

 traces of the metameric septa. There are often dental 

 organs, sometimes a crop, always a liver. The circu- 

 lation is lacunary ; the blood clear (rarely coloured), 



Fig. 31- 



: of a Worm ; i, i, i, infercnt vessels ; 2, cephalic end ; 



ninalend. 1 ;utihi-< : i. i', auricles; 2, cephalic aorta; 2', abdo- 



..i 01 Laracllaibranch or Loligo. 1), heart of Octopus. E, heart 

 ropod. 



isculated, and propelled by a heart, which rc- 



>les a segment of the circulatory system of worms 



31), receiving blood from one or two pairs of 



dilated, transvrr.se vessels distended into auricles, or 



: Into dilated, branchial sinuses (Fig. 31, i, i , 



:i receive blood from UT- .^ills and empty it into 



a Longitudinal do , modified into a vntrirlr, 



usually straight, rarely Hexed on itself, and sending 



forward a cephalic (Fig. 31, 2;, and bak \\ards an 



