The Genus Riccardia in Chile. 203 



and antarctic regions. They are often placed in the subgenus 

 Mittenia, to which Gottsche originally gave generic rank. In these 

 dendroid species, although the resemblance to Hymcnophytum in 

 vegetative features is so close, the sexual organs are borne dorsally 

 on photosynthetic branches, and the protective structures asso- 

 ciated with the sexual organs and sporophytes are essentially the 

 same as in the more typical species of Pallavicinia. 



Another member of the Blyttiaceae which helps to throw light on 

 the affinities of the Aneuraceae is the large genus Symphyogyna, 

 which is mostly tropical in its distribution. So far as its vege- 

 tative features are concerned this genus is essentially like Pal- 

 lavicinia and contains both prostrate and dendroid species. It 

 agrees further in the position of the sexual organs, in the general 

 nature of their protective coverings, and in the structure of the 

 capsule. It is distinguished mainly by its total lack of a pseudo- 

 perianth. The sporophyte here, as in Riccardia, is protected by 

 a massive so-called calyptra, derived largely from a meristematic 

 zone below the fertilized archegonium and bearing a cluster of 

 unfertilized archegonia at its apex. 



The comparison of the genera here discussed will show that their 

 characters are not definitely distributed so as to form well-marked 

 groups of genera. If Hyiiicnophyfuin and Podomitrium are both 

 retained in the Aneuraceae, as is done by Cavers, the only important 

 difference between this family and the Blyttiaceae is derived from 

 the sexual branches, which are short and more or less differen- 

 tiated in the Aneuraceae and undifferentiated in the Blyttiaceae. 

 If Podomitrium is placed in the Blyttiaceae, as Campbell suggests, 

 then the only difference between the two families are those 

 derived from the capsule, and Hymenophytimi to a certain extent 

 forms a connecting link between the two. These and similar con- 

 siderations led Campbell and Miss Williams (4, p. 42) to the 

 conclusion that there was no adequate basis for separating the 

 Aneuraceae from the Blyttiaceae. The writer fully agrees with 

 this conclusion and suggests that the two families be combined 

 under the name Riccardiaceae. In this family the genera 

 Moerckia and Makinoa, which Cavers places in the Blyttiaceae, 

 should likewise be included. Moerckia is a genus of four north- 

 ern species and is often regarded as a subgenus of Pallavicinia, 

 while Makinoa is a well-marked monotypic genus of Japan. 



