CHILEAN SPECIES OF METZGERIA. 



301 



In the remaining cells, however, the thickenings are arranged more 

 irregularly and the median wall of each valve is entirely free from them. 

 In all probability these differences are specific in character, and it is 

 natural to assume that the capsule-valves 

 in Mctzgeria may be as useful in distin- 

 guishing closely related species as in the 

 related genus Riccardia. It is to be regret- 

 ted that Andreas does not indicate the 

 species from which his description was 

 drawn. 



Although no gemmae have been observed 

 in M . dccipiens, a single case of regenera- 

 tion from a marginal cell has been demon- 

 strated. The product of regeneration in 

 this instance bore a strong resemblance to 

 a gemma, but its true nature was made 

 evident by the zone of dead cells separat- 

 ing it from the rest of the thallus. Atten- 

 tion may be called also to the ease with 

 which the species reverts to a more 

 juvenile condition. The narrow and rela- 

 tively hairless thalli, which have been 

 described, represent cases of such rever- 

 sion, and these often reach a more extreme 

 state by losing their costae altogether, 

 thus becoming reduced to uniform, uni- 

 stratose bands of cells (Fig. 6, C). The 

 prevalence and long duration of these 

 reversionary forms have added to the dif- 

 ficulties of recognizing and defining the 

 species. 



In reducing M. dccipiens to doubtful 

 synonymy under M. nitida (see p. 272) 

 Stephani criticised Schiffner for basing a 

 new species on material so poorly devel- 

 oped that it could not be definitely deter- 

 mined. In the writer's opinion this 

 criticism is unjustified. In the first place 

 M. dccipiens was really based on M. 

 furcata var. decipiem of Massalongo, and 

 the figures drawn from Spegazzini's type specimen (11, pi. 28, f. 86) 



Fig. 7. Metzgeria decipi- 

 ens (Massal.) Schiffn. & 

 Gottsche. 



A. Cells from outer layer 

 of a capsule- valve, X 300 ; m, 

 median wall of valve. B. 

 Cells from the inner layer of 

 a capsule- valve, X 300; m, 

 median wall of valve. The 

 figures were both drawn from 

 a specimen collected at Corral 

 by Thaxter, No. 138. 



