162 RAYMOND C. OSBURN AND RUTH M. VETH Vol. XXII, No. 6 



EXPLAXATIOX OF PLATE. 



Figures 1 and 2 are from Osburn's Bryozoa of the Woods Hole Region. Figure 8 

 is modified fiom Calvet, Bryozoaires Ectoproctes Marins. Other 

 figures by the junior author. 



Fig. 1. An individual of B. armata (Verrill), the zooid retracted. The gizzard is 

 shown in partial side view (at G) and the spiral bristles of the collar 

 (at B). 



Fig. 2. Coriiplete intestinal tract, showing the oesophagus (O), gizzard (G), 

 stomach (S) and intestine (I). 



Fig. 3. Diagrammatic cross-section of gizzard showing circular muscles (M), 

 epithelium (E) and chitinous cone (C) with teeth. 



Fig. 4. Diagrammatic side view of a cone showing the arrangement of the teeth 

 and the thickened rim around the base. 



Figs. 5, 6 and 7. Camera lucida drawings of actual cross-sections of different 

 cones. Some of the differences in form may be due to the fact that they 

 are not cut quite in the same direction. 



Fig. 8. Cross-section of the gizzard of Bowerbankia for comparison. Note that 

 here each epithelial cell bears its own chitinous tooth. The enlargement 

 is much less in this figure than in the others. 



