Plate IV.

GILL SHAPES.

Fig. 1. Gills as veins; infundibuliform.

2. Gills rounded in front (anteriorly.)

3. Gills rounded behind (posteriorly.)

4. Gills lanceolate.

5. Gills ventricose.

6. Gills unequal; cap convex.

7. Gills adnexed.