126 Alexander W. Evans, 



each sex has been available for study. In the male plant the sexual 

 branches occurred in pairs and represented the basal secondary 

 branches of short photosynthetic systems. The inflorescences 

 averaged about 0.6 mm. in length and 0.35 mm. in width and were 

 less compressed than those of R. prchensilis, the narrow wings 

 being suberect but scarcely connivent. In the female plant the 

 sexual branches occupied the same position as the male branches 

 and showed no signs of growing beyond the archegonia. Unfor- 

 tunately the two involucres observed were so disintegrated that 

 their structure could not be made out; the "calyptras" were 

 immature, but one showed a distinct corona. It will be remem- 

 bered that Stephani's description of Aneura Savatieri was drawn 

 wholly from sterile material. 



It is not surprising that R. prehensilis and R. Savatieri have been 

 confused. They agree with each other not only in general appear- 

 ance and habit but also in certain important structural features, 

 such as the surface layer of papillose cells, the three-layered wings 

 of the branches, and the row of hyaline cells bordering the wings. 

 At the same time they can be clearly distinguished by means of 

 their vegetative characters alone. The most important of the dif- 

 ferential peculiarities are perhaps the following, some of which 

 have already been indicated in the foregoing description : in R. 

 prehensilis the axis is wingless or essentially so, the superficial 

 cells of the axis and its branches average a' out 20 ix and project as 

 distinct and often overlapping papillae with thin walls, and the 

 photosynthetic branch-systems are copiously branched and broadly 

 ovate in outline ; in R. Savatieri, on the other hand, the axis is 

 winged throughout, the superficial cells measure about 25 fx. in 

 width and project very slightly as indistinct and often thick-walled 

 papillae, while the photosynthetic branch-systems are less copiously 

 branched and narrowly ovate in outline. In all probability 

 Bescherelle and Massalongo separated the species clearly but 

 referred R. Savatieri to R. prehensilis and the true R. prehensilis 

 to R. eriocaula var. chilensis (see page 123). 



4. Riccardia Thaxteri sp. no v. 



Growing in intricate mats, brownish green varying to almost 

 black : thallus ascending to suberect from a prostrate basal portion, 

 the axis subterete and wingless below, flattened and often winged 



