658 JAMES L. KELLOGG 
Fig. 27  Lyonsia saxicola; 6, bay of mantle; f, foot; vg, inner demibranch of 
gill; og, outer demibranch of gill; ums, visceral mass. 
Fig. 28 Lyonsia saxicola; mantle edge from above; b, bay of mantle; fo, 
foot opening of mantle; so, supplementary opening of mantle. 
