204 The American Geologist. April, 1902. 
umerated above, since Dekayia aspera and its associates and 
Heterotrypa are usually frondescent or subfrondescent. 
In a zone slightly lower than the one that afforded the 
specimens of Dekayia ulrichi-lobata (in the same locality) 
and associated with the highest specimens of Dalmanella mul- 
tisecta* seen, occurs a form that combines to a remarkable de- 
gree the characters of Dekayia, Heterotrypa, and Dekayella. 
The description of this form follows. 
Dekayia subfrondosa n. sp. 
PL. IX, F1GS..7, 8; PL. X, FIG. 3; Pu. XI, PIG. 1. 
Zoarium growing upward from an expanded cylindrical basal at- 
tachment into flat fronds of a thickness of 10 mm. to 15 mm. and a 
breadth of as much as 60 mm. A specimen hearly complete, except 
the cylindrical base has a height of 110 mm. The frond has a ten- 
dency to give off compressed branches along the free edges. Entire 
surface covered with small rather abruptly elevated monticules with 
an average diameter of 1.5 mm. From 12 to 13 occupy one square centr 
meter. At the apices of the monticules the cells are smaller than the 
average. Cells mostly of one kind, 0.25 mm. in diameter, 40 cells to 
the cm. 
The internal structure of this species as seen in tangential sections 
is highly instructive. In tangential sections cutting the mature region 
the cells are seen to be rather thin walled, the walls of adjacent zo- 
cecia being apparently amalgamated. That this is not the case is 
well shown in fig. 8, Pl. X, where the section cuts a portion of the 
zoarium that has been fractured and infilled with calcite along the 
fracture. The zocecia are spread apart, the wall formerly apparently 
common to two zocecia being now half on one side, half on the other 
side of the calcite seam. Where an acanthopore is present the zocecial 
wall separates from it cleanly. Indeed the acanthopore is sometimes 
left completely isolated in the calcite, showing that these structures 
belong to neither zocecial wall. The attention of those who deny the 
duplex character of the interzoccial wall should be called to this 
phenomenon. 
Only a moderate number of small tubes are seen throughout the 
main part of ordinary tangential sectinos. Fig. 8, Pl. IX, shows a 
cluster of small tubes in a portion of a section in which the walls 
are also thicker than is usual. Tangential sections of the branchlets, 
however, present almost identically the same appearance as sections 
of D. ulrichi robusta (pl. TX, fig. 4). 
* Other common members of this fauna are: Dekayia ulrichi-robusta, D. 
perfrondosa (Heterotrypa frondosa Ulr.) Callopora dalei, C. sigillaroides, 
Constellaria constellata, Escharopora pavonia, Homotrypa curvata, H., Cur- 
vata (ramose variety). Strophomena planoconvexa, Platystrophia dentata, 
Plectorthis plicatella, Zone 25 ft. thick. 
