SPEERSCmTEIDERA. 47 



Instead of the normally vertical, passing then into elongated 

 and pendulous forms, of the first family, we have here normally 

 horizontal, and leaf-like lichens. But we found the former 

 becoming dilated and sub-foliaceous, especially in the more cen- 

 tral groups, and finally depressed; and these central groups of 

 Usneei may be said to expand now into the new family before 

 us. Its near neighbourhood to the preceding is evinced still 

 further by ascendant forms already alluded to, which, taken 

 without regard to their whole history, might well pass for mem- 

 bers of the Usneei. Speerschneidera, though sufficiently 



recedent in its in fact fruticulose thallus, the under surface of 

 which differs only in colour from the upper, has yet clearly the 



horizontal vegetation, and habit. Theloschistes may be said 



to combine, in one most natural group, the habit, now of Rama- 

 Una, and now of Evernia, with that of Parmelia. The genus 



last-named is the centre and type of the Parmeliei ; but it dis- 

 plays also, as does Physcia, in occasional but striking forms, the 

 same tendency to revert to ascendant and Evernioid conditions. 

 Pyxine is a small cluster of strictly foliaceous lichens, dif- 

 ferenced from Physcia by the fruit-character. 



From the point of view of the spores, the centre of the 

 Parmeliei is seen to be Parmelia, of the Colourless Series; filling 

 here the place which is occupied by four genera in the Usneei, 

 and offering analogues, we had almost said, to each. From 

 Parmelia deviates Theloschistes, of the same series, the analogue 

 of Mamalina; while a still greater divergence in the same 

 -direction is exemplified in Speerschneidera, which it seems possi- 

 ble to consider as in like relation to Eoccella. In the Brown 

 Series, on the other hand, the place corresponding to Thelos- 

 chistes is taken by Physcia, the analogue here of AUctoriam the 

 Usneei ; and finally by Pyxine, an extreme and aberrant type, 

 anticipating, as respects the fruit, the similarly exceptional, next 

 succeeding family. Genera p. 17. 



VIII. SPEERSCHNEIDERA, Trev. 



Apothecia scutellseform. Spores from ellipsoid becoming 

 obloog and dactyloid; 2-4-locular; colourless. Spermatia 

 oblong j on sparingly articulate sterigmas. Thallus orbic- 

 ular, depressed-fruticulose, terete, dichotomously many- 

 cleft, cartilagineous-coriaceous; fibrils deficient on the under 

 side. 



