ASTERIAS FOR B ESI 



179 



is the aboral sinus-ring, which gives rise to five genital sinuses. 

 The system of lacunae is inclosed in the septa of the system of 

 sinuses. It is composed of an oral lacuna ring, five radial 

 lacuna, transverse lacuna, axial lacuna, aboral lacuna ring and 

 five genital lacuna. 



The axial organ is simply a glandular part of the axial lacuna, 



nrd. 



FIG. 35. Nervous system of a starfish after Delage and Herouard. 

 n. osc, oesophageal nerves; an. oes, cesophageal nervous ring; an. c, ecto- 

 neural oral ring; nh, hyponeural radial nerve; an, hyponeural oral ring; 

 np, transverse (pedal) nerves; avnls, nervous rings of suckers; nrd, ecto- 

 neural radial nerve; nd, deep dorsal nerves. 



in which the lacuna forms a plexus. It is connected with the 

 axial sinus by numerous pores. 



The axial sinus, axial lacuna with the axial organ and the 

 hydrophoric canal are all together inclosed in a peritoneum and 

 form the axial complex. 



The nervous system consists of a superficial or ectoneural, 

 deep ventral or hyponeural, and deep dorsal or entoneural sys- 



