408 INTRODUCTION TO CRYPTOOAMIC BOTANY. 



Omphalaria Girardi, in the Flora of Algiers, tab. 18. Some- 

 thing of the same kind is figured in the same work in Endo- 

 carpon Dufourei. It is therefore very desirable that an 

 accurate comparison should be made, as it may throw further 

 light on their affinities. I have unfortunately not the proper 

 materials at hand to work the matter out. 



444. A portion of the Collemals have been noticed under 

 Lichinei ; and to the genera there noticed Obryzum may be 

 added, on account of its conceptacular fruit. Synalyssa makes 

 a near approach to Lichinei in this respect, as it does also in 

 habit, but the disc is ultimately well opened. The same may 

 be said of the curious genus Myriangium. In the two origi- 

 nal species the disc is mostly veiled ; but in M. Curtisii, Berk, 

 and Mont, which is far the finest, it is as open as in any Col- 

 lema or Leptogium. The cells in which the asci are contained 

 may be compared with the arrangement of the asci in Graphis 

 Leprevostii (Fig. 84, c). Myxopuntia, Mont., approaches 

 very near to Collema Schroderi, differing slightly in the 

 construction of the thallus, and is remarkable for the opuntioid 

 constriction of the subfastigiate branches. The genus Collema, 

 including Leptogium, is universal, and many of its species are 

 very widely diffused. Myriangium occurs under the same 

 species in the south of Europe, extending as high as the Chan- 

 nel Islands, and crossing the Mediterranean to Africa, and on 

 the Swan River in Australia. Myxopuntia has been found 

 only in northern Africa, where Omphalaria produces two 

 species, a third occurring on the rocks of cataracts amongst the 

 Vosges mountains. 



7. Lecidinei, Fr. 



Disc contained in a proper excipulum, open from the begin- 

 ning, and in age frequently obliterated ; thallus various. 



445. We have here, again, a group containing very numerous 

 species, and differing from each other extremely in habit. 

 Many are amongst the most obscure of Lichens, adhering so 

 closely to their matrix that they cannot be separated from it 

 without destruction ; while others are amongst the more noble 

 forms, presenting erect branched fronds, often clothed with 

 foliaceous scales, and of highly beautiful colours. Their dis- 



