CHILEAN SPECIES OF METZGERIA. 287 



wings are involute and the costa so strongly incurved that the apex 

 almost reaches the base, the branch thus acquiring a spherical or sub- 

 spherical form. x\ccording to Stephani the surface is smooth, but 

 this is rarely the case, from one to a dozen hairs being usually present 

 (Fig. 3, C). 



If Stephani's descriptions of M . Lechleri and M. corralensis are com- 

 pared it will be seen that they agree in most important respects, even 

 though he places M. Lechleri among the Furcatac. The most impor- 

 tant differences that he brings out are derived from the costae and alar 

 cells, the features of which in typical M. corralensis have already been 

 discussed. According to his description the costa of M. Lechleri is 

 bounded both dorsally and ventrally by four rows of cortical cells, 

 while the alar cells have firm walls distinctly thickened at the angles. 

 The study of Lechler's Arique specimens in the Mitten Herbarium, 

 which agree in most respects with Stephani's description, brings out 

 the fact that the cortical costal cells are inconstant in number, just 

 as in M. corralensis. The alar cells, moreover, although slightly 

 thickened, do not show conspicuous trigones; in fact it is usually 

 difficult to make them out at all. Since the differences between the 

 species thus break down, and since the Arique specimens are essentially 

 like Krause's type, the writer feels convinced that the two species are 

 synonymous. 



The importance of gemmae in distinguishing species of Metzgeria 

 has already been emphasized by the writer in another connection (4). 

 In M. corralensis the gemmae are dorsal and are borne on ordinary 

 vegetative branches, the growth of which is apparently unlimited. 

 As in M . crassipilis (Lindb.) Evans of the eastern United States (see 4, 

 p. 282) and other species having dorsal gemmae, many thalli are not 

 gemmiparous at all, while others produce the gemmae in great pro- 

 fusion. In the case of M. corralensis the early stages of development 

 have not been studied, but their adult features will be described. 



At the time of separation (Fig. 3, D) the gemmae vary somewhat 

 in size but most of them are 0.18-0.27 mm. long and 0.16-0.24 mm. 

 wide; they may be orbicular, but the width is usually a little less or a 

 little more than the length. A gemma is six to eight cells across and 

 has a single apical cell. What may be described as the dorsal surface 

 is convex and usually shows from two to six short and rudimentary 

 hairs. The gemma bears in addition from three to eight marginal 

 hairs on each side, and these may be truly marginal or slightly dis- 

 placed to the ventral surface, which seems otherwise to be perfectly 

 smooth. 



