1909] Evans,— Notes on New England Hepaticae,— VII 187 
plane, the marginal cilia to occur singly, and the postical surface of the 
wings to be usually pilose. The marginal cilia are further distin- 
guished by being slightly displaced to the postical surface and therefore 
not clearly visible from above. In M. conjugata, on the other hand, 
the thallus is said to be convex, the marginal cilia to occur frequently 
in pairs, and the postical surface of the wings to be practically free 
from cilia. Unfortunately, as Limpricht and others emphasize, most 
of these vegetative characters are subject to a good deal of variation, 
and it is not infrequent to find specimens in which the cilia are either 
sparingly developed or absent altogether. Even when present they do 
not always show the peculiarities of arrangement detailed above. 
Marginal cilia in pairs, for example, may occur in combination with 
scattered postical cilia, and wings of the thallus which are smooth 
on both surfaces may show marginal cilia borne singly. Тһе position 
of these unpaired cilia, moreover, may also vary, being sometimes truly 
marginal and sometimes displaced to the postical surface. On ac- 
count of the inconstancy of these vegetative characters Limpricht * 
was inclined to look upon M. conjugata as nothing more than a robust 
and normally developed form of M. furcata, due to a favorable environ- 
ment, and Boulay,’ still more recently, was unwilling to accord it more 
than subspecifie rank. Most writers, however, accept both species 
without question, and this seems the wisest course to pursue since 
specimens with sexual branches usually show the specific characters 
clearly. The impossibility of determining all sterile material is by no 
means unusual in other genera of the hepaticae. 
Although certain of the characters already mentioned are seen to be 
untrustworthy, M. furcata often produces peculiar organs of vegetative 
reproduction, which enable us to determine sterile specimens without 
difficulty. These organs have long been known but it is only lately 
that they have been at all emphasized from a taxonomic standpoint. 
They are in the form of marginal gemmae, or propagula, and are ovate 
to ligulate in outline according to the stage of their development. 
They are at first only one cell thick throughout but usually acquire a 
median costa sooner or later. ‘The gemmae are frequently developed 
in great abundance, and Goebel? considers their production to be a 
direct result of unfavorable conditions. Lindberg described these 
1 Cohn, Krypt.-Flora von Schlesien 1: 441. 1876. 
2 Musc. de la France 2: 170. 1904. 
з Flora 83: 69-74. 1898. 
