i86 



MORPHOLOGY OF INVERTEBRATE TYPES 



L pel 



.n.rd. 



cn.pd__L 



nmcl. 



n.cuL 



FIG. 37. Relation between the nervous and ambulacral systems in the 

 arm of a brittle star after Delage and Herouard. n. cut, cutaneous nerve; 

 en. pd, pedal canals; g. pd, pedal ganglia; ;;.. cpn, epineural nerve; g. epn, 

 epineural ganglia; pd, ambulacral tubes; n. rd, epineural radial nerve; 

 nh, hyponeural radial nerve; en. rd, radial canal; n. md, nerve of inter- 

 vertebral muscle. 



disc. Hepatic glands are absent. The stomach is a blind sac. 

 Intestine and anus are wanting. The ambulacral system pre- 

 sents the following differences: the hydrophone canal opens on 



