756 Proceedings of the Royal Irish Academy. 



arrangemeiit ; M. M. Hariot, Karsten, and Hansgirg having all agreed 

 in absorbing it in Phyeopeltis/ 



The question was reviewed subsequently in a very valuable paper 

 by M. Hariot (17). He points out that the Mycoidea of Cunningham 

 is identical with the genus Cephaleuros of Kunze established as far 

 back as 1827, and that Mdbius' Phyllactidium tropicum and de Tonis' 

 Sansgirgia flalelligera should both be included in Phycopeltis. 



Lastly, Karsten (16) in summarizing the whole family agrees with 

 Hariot in substituting the name Cephaleui'os for Mycoidea. He pro- 

 poses to use this generic term for all those peltoid Trentepohliacese 

 which sometimes consist of more than one cell-layer ; which have 

 usually rhizoids penetrating the leaf, and which bear several sporangia 

 on long filaments. 



The name Phycopeltis, on the other hand, is restricted to those in 

 which the thallus consists of one cell-layer only, and is entirely epi- 

 phytic : the sporangia are borne singly on short stalks. 



A third type is also raised to the rank of a genus, for which, very 

 unfortunately the name of Chroolepus is revived. It has a thallus like 

 that of Phycopeltis, but bears long slender hairs with lateral sessile 

 protuberances. These are regarded by the author as sporangia. 



So far then as the genus Phycopeltis is concerned, we have well- 

 defined the three species described by Karsten which may be sum- 

 marized as follows : — 



1. Ph.. treubii. — Thallus radially lobed at the margins, with red- 

 brown Heematochrome. Disc-sporangia elongate and terminal. Spo- 

 rangia on pedicels of two to six cells. 



2. Ph. maritiraa. — Thallus small, discoid, with red-brown Haema- 

 tochrome ; sporangia at the ends of cell-rows slightly raised, but 

 without any definite pedicel. 



3. Ph. aurea. — Thallus yellow; crenately lobed at the margin; 

 Disc-sporangia elongated and terminal ; sporangia carried erect on 

 unicellular sinuous pedicels longer than the sporangium. 



Pa addition to these, there are the European species which have in 

 no case any definite form of stalked sporangia, and which must there- 

 fore be left for the present as species " incertae sedis." 



These are Phycopeltis epiphyton, Mill ; Ph. arundinacea, Mont ; 

 and Ph. fiabelligera, de Toni, sp. (= Phyllactidium tropicum, Mob.) and 

 Sansgirgia Jlabelligera, de Toni. 



1 See also De Toni, " Intorno alia indentita del Fh. tropicum con la Sansgirgia 

 jiabellata de Toni, Xotaiisia, 1889, Iso. 1, p. 703 ; and De Toni and Saccardo — 

 Nuova Notarisia, 1890. 



