The Genus Riccardia in Chile. 201 



female branches are more like those of Riccardia, the archegonia 

 being borne on the dorsal surface, but the wings are never cut 

 up into teeth or laciniae and no other involucral structures are 

 present. After fertilization a massive calyptra. covered over with 

 hairs and derived largely from the venter of the archegonium, is 

 developed. 



It has been clearly shown that the genus HynienopJiytnm as 

 earlier defined includes two distinct genera, to which the names 

 Umhraculuni and Podomitrimn have been applied (see Cavers, 5, 

 p. 68, and Campbell and Miss Williams, 4, p. 41). If the name 

 Hynicnopliytmii is restricted to the first of these genera, which 

 includes H. flahcllatnm of New Zealand and Australia and its few 

 allies, the thallus shows a differentiation which may be compared 

 with that found in R. Thaxtcri. In other words the basal portion 

 forms a prostrate wingless rhizome and then curves upward and 

 develops a richly branched photosynthetic system borne on a long 

 stalk, which is likewise wingless throughout the greater part of its 

 extent. Where the basal portion begins to curve upward it gives 

 off a new prostrate portion which in turn forms a new photosyn- 

 thetic system. By a repetition of this process a sympodial rhizome 

 is formed, upon which the aerial portions seem to be laterally borne 

 (see Goebel, 11, p. 250, /. 149). The branches of the latter arise 

 by a series of closely repeated dichotomies and are strongly flat- 

 tened and winged, the whole system forming a semicircular and 

 deeply lobed expansion bearing a strong resemblance to a leaf of 

 some filmy fern. On the whole the differentiation here is more 

 definite than in R. Thaxteri, although the thallus appears less 

 complex. 



The sexual branches of HymenopJiytmn are borne on the photo- 

 synthetic branch-systems and are ventral in position, as in Metz- 

 geria, but the male branch is so reduced that the antheridia, each 

 in a deep depression, seem to form a sessile cluster on the thick- 

 ened median portion of the thallus. The female branches are more 

 like those of Metsgeria and are in the form of short scales. After 

 fertilization, in addition to the calyptra, a tubular sheath or pseudo- 

 perianth is developed around the young sporophyte. 



The elaterophore of Metsgeria is less massive than that of 

 Riccardia and the capsule wall is more delicate in texture, although 

 the cells of the inner layer still show half-annular thickenings on 



