172 Alexander W. Evans, 



archegonia and scarcely evident wings, the marginal cells pro- 

 jecting slightly or not at all. 



18. Riccardia Negeri (Steph.) comb, nov, 

 Aneura Negeri Steph. Bull. Herb. Boissier 7: 747. 1899. 



Specimens examined : without date or definite locality, south- 

 ern Chile, \F. W. Neger 34 (B., type of Aneura Negeri). Known 

 only from the type locality. 



In describing his Aneura Negeri Stephani emphasizes the great 

 uniformity which the thallus exhibits and its broadly rounded 

 margins. A uniformity in structure and appearance implies that 

 the characters of the plant are rather negative, but fortunately these 

 negative features are supported by more positive peculiarities, 

 when the histology of the thallus is taken into consideration. The 

 scanty type material throws little light on the habit of the plant ; 

 it shows nothing of the way in which the thallus is attached to the 

 substratum, and it gives but little information about the female 

 inflorescence and none at all about the male. It is sufficient to 

 show, however, that R. Negeri is amply distinct and without close 

 relatives among the other Chilean species of the genus. 



The plants, which are apparently loosely tufted and erect, are 

 light to dark brown in color and firm and rigid in texture. Neither 

 stolons nor rhizoids have been observed. The axis (Fig. 10, A) 

 is usually 3-5 cm. long but may attain a length of 7 cm. according 

 to Stephani. The width is mostly 1-1.5 mm. and the thickness 

 about 0.3 mm. Except toward the thick rounded edges, wholly 

 destitute of wings, the two surfaces are plane or nearly so, 

 although the dorsal surface may show a slight convexity and the 

 ventral surface a still slighter concavity. In the median portion 

 the thallus is mostly ten to twelve cells thick, but toward the mar- 

 gin (owing to the greater size of the cells in this region) it is only 

 about eight cells thick (Fig. 10, C). The cells of the outermost 

 layer are about 14 /x wide and usually 30-50 /a long, although more 

 nearly isodiametric cells are not infrequent. On the lower surface 

 a broad median band of this layer is composed of unusually 

 delicate and short-lived cells, which can be seen clearly only in the 

 youngest part of the thallus. In the older parts vestiges of these 

 ephemeral cells can usually be detected, but the second layer 



