ECHDs T ODERMATA. 



31 



ORDER IV. HOLOTHUROIDEA (Sea-cucumbers). 

 Sub-ord. 1. Apneumona. 



Fam. a. Synaptidae. Synapta, Chirodota, Anapta. 

 Fam. &. Oucinolabidse. Oncinoldbes. 



Sub-ord. 2. Pneumonophora. 



Fam. a. Molpadiidse. Molpadia. 

 Fam. b. Aspidochirotee. Holothuria. 

 Fam. c. Dendrochirotse. Cucumaria (Pentacta), Psolus, 

 Thyone. 



(Selenka,Beitrtige zur Anatomic und Systematik der Holothurien, Zeitsckr. 

 fur Wiss. Zool., 1867-68. Semper, Reisen im Archipel der Philippinen, 

 1868.) 



p 



L-l 



"- a, 



Fig. 27. Holothuroidea. Semi-diagrammatic longitudinal section of a Holothurian. t, 

 Tentacles ; r, Calcareous ring at the base of the tentacles ; p, Polian vesicle ; s, Sand-canal ; 

 i i i, Alimentary canal ; g, Duct of the reproductive ^organs ; d, Cloaca ; a, Anus ; 1 1, res- 

 piratory tree. 



