MOLLUSCA-ECHIUROIDEA 23 



Order EULAMELLIBRANCHIA 



Cardium (cockle); Ostrea (oyster); Mya (gaper); 

 Anodonta ( = Anodori) (swan-mussel) ; Unio (pearl- 

 mussel); Tellina (ieWin); Pholas (piddock); Teredo 

 (ship-worm) 

 Order SEPTIBRANCHIA 



Poromya (gaper) ; Cuspidaria 



Class CEPHALOPODA 



( = SiPHONOPODA) Order TETRABRANCfflA 



Nautilus (pearly-nautilus) 

 Order DIBRANCHIA 



Sub-order Decapoda* 



Architeuthis: Sepia ( = Eusepia) (cuttle-fish); Loligo 

 (squid); Spirula 



Sub-order Vampyromorpha 

 Vampyroteuthis (vampire squid) 



Sub-order Octopoda 

 Octopus i= Polypus) (octopus); Argonauta (paper- 

 nautilus); Eledone (lesser octopus) 



Phylum SIPUNCULOIDEA2 



Golfingia ( = PhascolosomaY ; Phascolosoma 

 ( =Physcosoma, PhymosomaY ; Sipunculus; 

 Dendrostomum; Aspidosiphon; Phascolion 



Phylum ECfflUROroEA^^ 



Order ECHIUROINEA 



Bonellia; Echiurus; Thalassema; Ochetostoma 

 Order XENOPNEUSTA 



Urechis 

 Order HETEROMYOTA 



Ikeda 



* See Eucarida, p. 31. 



* The Sipunculoidea and Echiuroidea have also been grouped with the Priapulida, p. 17, as Gephyrea. 



» Golfingia LankesteT=Phascolosoma (auct.). Phascolosoma F. S. Leuckan= Physcosoma Selenka, see 

 Fisher (1950). 



« Poeobius is sometimes put in this phylum and sometimes in phylum Poeobioidea. In all probability, 

 however, it is an aberrant polychaete, p. 24. 



