208
Fig. 2.52 External membranous brood sac of Aetea anguina .
( A ) Autozooid with retracted tentacles and brood sac. ( B ) Autozooid
with extended tentacle crown (shown by dotted lines ). Bottom : longitudinal section of terminal area of autozooid and membranous brood
sac (From Cook 1977b , courtesy of Oxford University Press, http://icb.
oxfordjournals.org/content/17/1/55.short ). Abbreviations: a attached
proximal part of autozooid, b brood sac, с calcifi ed part of brood sac, e
erect distal part of autozooid, f frontal membranous wall, o operculum,
t tentacles
2 Cheilostome Brood Chambers: Structure, Formation, Evolution
Fig. 2.52 External membranous brood sac of Aetea anguina .
( A ) Autozooid with retracted tentacles and brood sac. ( B ) Autozooid
with extended tentacle crown (shown by dotted lines ). Bottom : longitudinal section of terminal area of autozooid and membranous brood
sac (From Cook 1977b , courtesy of Oxford University Press, http://icb.
oxfordjournals.org/content/17/1/55.short ). Abbreviations: a attached
proximal part of autozooid, b brood sac, с calcifi ed part of brood sac, e
erect distal part of autozooid, f frontal membranous wall, o operculum,
t tentacles
2 Cheilostome Brood Chambers: Structure, Formation, Evolution