XVII. Mollusca / by Nils Hj. Odhner -- XVIII. Studies of the birds in north west Australia / by Rudolf Soderberg -- XIX. Holothurioidea / von Sven Ekman -- XX. Serpulimorphe Anneliden / von K.E. Johansson -- XXI. Echinoidea / by Th. Mortensen -- XXII.
Madreporaria / by Folke Folkeson -- XXIII. Crinoids / by Torsten Gislen -- XXIV. Bryozoen / von Ernst Marcus.
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