﻿250 MONOGRAPH OF LICHENS FOUND IN BRITAIN. 



Part I.— the present volume— deals with about one-half of the 

 subject reckoned in species, or more than two-thirds reckoned in 

 genera. Of the 92 genera described in the synopsis at the beginning, 

 66 are worked out in detail. 7 genera are comprised in Family I. 

 —the Ephebacei; 12 in Family II.— the Collemacei; and of Family 

 III.— the Lichenacei—47 genera are given, taking us to the end of 

 I rrm/aria, and leaving to Part II. of the Monograph from Lecidea 

 onwards. The bulk of Part II. will thus be occupied with the two 

 large genera Lecidea and Verrucaria, and the tribe Graphidei. The 

 remaining tribe Myriangiacei contains one solitary genus. Upon 

 comparing Part I. with the corresponding ground mapped out in 

 the third edition of Leighton's Lichen-Flora, published in 1879, it 

 will be found that 459 species in Leighton (or Leigthon, as conti- 

 nental botanists not infrequently prefer to spell the name) have 

 increased to 580 species in Crombie ; and 53 genera to 66. Of the 

 genera employed by Leighton, one— Sirosiphon— is omitted as in- 

 sufficiently known : and three— Psoroma, Squamaria, and Placodium 

 —are treated as subgenera of Lecanora. On the other hand, seventeen 

 genera, thirteen of which have been coined in the Nylanderian mint, 

 are put in circulation by Mr. Crombie. Thus in the family Ephebacei 

 we have Euopsis Nyl. comprising two species split off from Pyre- 

 nopm+ EpKebeia Nyl. one species from Ephebe, and Magnmpsi, Nyl. 

 one species, M. argilospila, which is synonymous with Leighton's 

 Verrucaria arenicola. In the family CoUemacei, Lkhiniza Nyl. con- 

 tains one rare species from Kenmore, in Perthshire, and " is most 

 probably allied to Lichina." Schizoma Nyl. takes one species from 

 Collema, and ColUmodium Nyl. one from Collema and six from Lepto- 

 gvum, with one recruit not known to Leighton. Dendriscocatdon 

 Nyl. is, as is also the case with one in the following family, a 

 pseudo-genus, and " is only a leprarioid condition of Leptogium." 

 Its single species, D. bolacinum Nyl., "constitutes the glomeruli of 

 Rumolia glomulif era"— or rather R. amplissima, for the latter is the 

 accepted name on p. 275, where the species is described. In the 

 family Lichenacei ten genera are added. Of these, one— Leprocatdm 

 Nyl.— is a pseudo-genus, and is only " a fruticulescent Lepra via " 

 with a " superficial resemblance to Stereocaulon, to which, however, 

 it is not even allied." Another pseudo-genus is Leproloma Nyl., 

 which has a leprarioid thallus, and for this reason is separated off 

 from Amphiloma (a genus confined to the tropics), under which 

 name it appeared in Leighton. Its true position is uncertain, as 

 its fructification has never been seen. Stenocybe Nyl. derives its 

 three species from Calicium; while Parmeliopsis Nyl. (two species), 

 Lobarina Nyl. (one species), Lobaria Hoffm. (one species), Peltidea 

 Ach. (two species), and Gyrophora Ach. (ten species), are established 

 at the expense of Parmelia, Stictina, Sticta, Peltigera, and Vmhili- 

 caria respectively. The true Gyrophora erosa of Acharius, a very 

 scarce Scotch plant, is defined and separated off from G. torrefacta 

 Cromb. (G. erosa of other British authors). Pannularia Nyl. and 

 Coccocarpia Pers., with eight and one species respectively, are lopped 

 off from Pannaria. Varicellaria Nyl. contains " only a single species 

 .... which has recently been recorded as British." It is remark- 

 able for possessing " spores which are the largest observed among 



