EVANS—THE NORTH AMERICAN SPECIES OF ASTERELLA. 255 
The peduncle is sometimes white or pale green but usually shows 
more or less purple pigmentation. In most species it bears scattered 
filamentous scales, these tending to be more numerous in the apical 
portion, but in certain species the scales are scanty or even absent 
altogether. The peduncle arises from the apex of a branch, the 
growth of which is almost invariably brought to an end. This 
branch is sometimes elongated and sometimes very short; in the 
latter case it is usually ventral in position, although in some instances 
one or both branches of a dichotomy may give rise to female recep- 
tacles almost immediately. Leitgeb mentions a single specimen of 
A. ludwigti (Fimbriaria pilosa) in which an abortive female recep- 
tacle failed to limit the growth of a branch, and makes the deduction 
that such limitation must therefore be a secondary, rather than a 
primary, result of the development of the receptacle and that the 
latter is dorsal in origin. No examples of this kind have come to the 
attention of the writer, but the remarkable conditions sometimes 
found in A. californica may be noted in this connection. In this 
species, as figures by Howe? clearly show, the receptacle may grow 
out from the bottom of a dichotomy, an ordinary branch ap- 
pearing on each side. This would seem to indicate a dorsal origin, 
the apical region of the branch continuing its growth but undergoing 
a dichotomy at once. The subject, however, deserves further study. 
The disk of the female receptacle, as already noted, has been the 
subject of considerable discussion. In the earliest developmental 
stages described by Leitgeb the archegonia, three or four in number, 
had already become displaced to the ventral surface through the 
active intercalary growth of the dorsal portion. They appear singly 
in low grooves, evenly distributed near the periphery, which at first 
shows no indication of lobing. Alternating with the archegonia are 
short furrows with rhizoids, continuous with the furrow of the pe- 
duncle. Since the archegonia occurred singly, Leitgeb concluded that 
the receptacle did not represent a branch system. Campbell found, 
however, that the archegonia of A. californica did not occur singly 
but in short radiating groups, those of each group arising in acro- 
petal succession, and he concluded that in this species the receptacle 
must represent a branch system. According to the ideas of Goebel 2 
such distinctions, which Leitgeb considered characteristic of the 
groups Operculatae and Compositae, are less important than has 
been supposed. In both cases the receptacle represents a branch; if 
the receptacles are similar in other respects, it is not of much signifi- 
cance whether this branch becomes subdivided or not. 
*Mem. Torrey Club 7: pl. 95, f. 1-5. 1899. 
* For a discussion of these ideas see Evans, Bull, Torrey Club 42: 271-274. 
1915. 
