224 Evans : HEPATICAE OF PUERTO RICO 
segments. In the younger segments, however, there is often an 
anticlinal wall formed in the most external cell. So far as ob- 
served the basal quadrants always divide by a single periclinal 
wall. The attachment of the gemma is markedly excentric, and 
the separation takes place just as in Cololejeunea, a slightly project- 
ing stalk cell being left behind. 
The curious organs of attachment, noted in the genera Colole- 
jeunea, Leptocolea, and A phanolejeunea, are developed also in the 
gemmae of Diplasiolejeunea. In the vast majority of cases there 
are three such organs on each gemma. One arises from the outer 
most cell of one of the oldest segments on one side of the median 
wall, while the other two arise from the outermost cells of the 
second segments cut off from the apical quadrants. In a single 
instance a gemma with four organs of attachment was observed, 
one arising in each of the oldest segments. It will be noted 
that in contrast to Cololejeunea and its allies the basal quadrants 
play no part in the development of the organs of attachment. 
The mature gemma consists of an oval plate of cells broader than 
long. The margin is entire, and the apical cell in each half is 
clearly visible, being sometimes situated in a slight depression. 
The gemmae in D. pellucida, D. unidentata, and D. Rudolpmana 
are essentially alike. 
The germination follows the same course as in Cololejeuned, 
one of the apical cells of the gemma functioning directly aS the 
apical cell of the leafy shoot without the interpolation of a thalloid 
structure (TEXT FIGURE 2, C). The leaves at the base of the shoot 
are rudimentary and have no corresponding underleaves, but the 
characteristic features of the genus are very quickly acquired. In 
one case both apical cells had given rise to shoots, but one wae 
much better developed than the other. 
YALE UNIVERSITY. 
