CHILEAN SPECIES OF METZGEBIA. 283 



female branches themselves were so old and battered that their dis- 

 tinctive features could not be determined. 



The three synonyms included under M . decrescens may now be con- 

 sidered. The first, M. terricola, was based on two specimens, one 

 collected by Savatier on Desolation Island and the other by Dusen on 

 Newton Island. According to Stephani M. terricola shows a varia- 

 bility in the number of cortical costal cells, comparable with what is 

 found in M. decrescens. The wings of the thallus, moreover, are 

 revolute in much the same way, while the cells are said to average 

 about 54 X 36m, measurements which diverge but slightly from tho e 

 given for M. decrescens. The following represent the most important 

 differential characters indicated: the presence of a few setulae on the 

 ventral surface of the thallus and the occurrence of the marginal hairs 

 in pairs. 



In Savatier's specimens, which may perhaps be regarded as the 

 type, the costa is essentially like that of the type specimen of M. 

 decrescens; and, although ventral hairs are sometimes present on the 

 costa, this is equally true of M. decrescem. The marginal hairs, more- 

 over, so far as the writer can determine, are invariably borne singly. 

 In Dusen's material some of the thalli are like Savatier's, but other 

 show crowded marginal cilia in pairs. The latter, however, are associ- 

 ated with costae that are bounded constantly, both dorsally and 

 ventrally, by only two row- of cortical cells, while the cells of the 

 revolute wings are considerably larger, averaging about. 70 X \0 p. 

 In the writer's opinion the thalli with the geminate marginal hairs 

 should be referred to M. hamata, although they evidently formed a 

 part of the material from which the description of M. terricola was 

 drawn. If these thalli are eliminated there is apparently nothing 

 whatever to distinguish M. terricola from .1/. decrescens. The writer 

 regrets that he has not seen Herzog's specimens of "M. terricola" to 

 which allusion has already been marie ('see page 27 1 . 



The second synonym, M. longiseta, was based on a specimen from 

 the Strait- of Magellan, the collector's name not being given. In his 

 account of this species Stephani calls ait.ent.ion to the strongly con 

 thallus, the variable number of cortical co tal cells, the long marginal 

 hair- borne singly, and the alar cell- averaging about 54 X 36 n, four 

 characters which .1/. Umgiseta clearly -hare- with M. dt is. He 



mention- also the fact that the wings are two or three cells thick mar 

 the costa. This, as has been shown, is another characteristic feature 

 of M. decrescens, although the original description doe-, not allude to 

 it. The differential characters of M. longiseta are apparently drawn 



