THE SYNANGIATE NATURE OF DOLEROTHECA

Transverse sections through the distal region of a Dolerotheca specimen in a coal ball from the Calhoun coal of Illinois show the double rows of sporangia where they are free from one another. This leads to the conclusion that the sporangial rows should be regarded as extending inward from the campanulum cover rather than radiating outward from the center. This observation suggests that Dolerotheca is a synangium composed of many sporangial units of different lengths.