Howe : Riccia Beyrjchiana and Riccia dictyospora 163 



Hampe 1837," and in view of the little attention which the collec- 

 tion of the Ricciae has as yet received in this country it seems to 

 us that it is too early to suspect that everything in this connection 

 is not just as it purports to be. Herr Stephanas description 

 leaves little to be desired outside of a more detailed account of the 

 spores, which we have supplied below in course of comparison with 

 Mr. Harper's plant. The specimens collected by Mr. Harper 

 represent, we believe, a hitherto unrecognized species which we 

 would characterize as follows : 



Riccia dictyospora sp. nov. 



Thallus simple or once dichotomous, forming irregularly gre- 

 garious patches, finally oblong or elongate-oboyate, rarely sublin- 

 ear, 4-10 mm. x 1-2 mm., reticulate above, light green (when 

 dry) with at length a narrow dark-purple border ; median sulcus 

 acute and somewhat pronounced toward the apex ; ventral scales 

 entire, purple at maturity, slightly exceeding the thin submem- 

 branous ascending thallus-margins ; width of transverse sections 

 of the thallus 1.5-3 times their height, the ventral outline 

 rounded-convex or somewhat flattened, air-canals narrow and ver- 

 tical, special cells densely filled with a yellowish granular sub- 

 stance ( " oil-body " cells) usually abundant : primary epidermal 

 cells oval-papilliform, soon collapsing, leaving more or less per- 

 sistent cup-like vestiges : monoicous : antheridial ostioles not ele- 

 vated : spores brown, rather translucent, soon exposed by the 

 rupture of the overlying parts, 95-116 /x in maximum diameter, 

 scarcely angled, somewhat flattened, wholly destitute of wing-mar- 

 gins, almost uniformly areolate over entire surface, in optical sec- 

 tion appearing densely beset on all sides with short truncate 

 spines or papillae ; areolae of the outer face 8-12 ft in width, 

 often less perfect in the middle of the face; areolae of the inner 

 faces so similar to those of the outer as not to be readily distin- 

 guished at first sight, yet slightly larger and less regular, with 

 somewhat less elevated boundaries. 



On moist granite rock near Oconee River, Athens, Georgia 

 (alt. 183 m.), Roland M. Harper, June 26, 1900, no. 68a. 



In Riccia dictyospora the markings of the spore-wall are de- 

 veloped over its entire surface with a rare uniformity, the areolae 

 being carried over the rounded scarcely perceptible wingless angles 

 with little interruption. That there is, however, a difference in the 



Bull. Herb. Boiss 6 : 318. 1898. 



