Table of Genera of Physaraceæ.

I. Tubules of the capillitium having the granules of lime in them aggregated into roundish or angular nodules, with intervening empty spaces.

A. Outer surface of the sporangium destitute of lime.

B. Outer surface of the sporangium invested with granules of lime.

a. Stipe prolonged within the sporangium as a columella.

b. Stipe never entering the sporangium.

II. Tubules of the capillitium with the granules of lime in them distributed throughout their entire length.