8 THE DETERMIXATTOX OF LTCHEKS TX THE nELI> 



(//) Cephaloclia are tubercles containing filaments of the normal 

 fungal constituent but with a foreign algal constituent (usually 

 Nosfoc). They may be externally or internally jDlaced. 



(/) Only large specimens of some Physcias (e. g. P. aipolia) have 

 lobes broader than 4 mm. 



(j) Many species (1, 8, 9, 10, 15-19, 23, 21, 30, 31, 84) of 

 Parmelia may have lobes broader than 4 mm. Other species not 

 enumerated may exceptionally have large lobes. P. pliysodes has no 

 rhizinse beneath. When soredia are present in Phi/scia they usually 

 occur as rounded bodies (soralia) on the surface of the thallus ; in 

 Parmelia they are seldom orbicular in form and often occur on the 

 margins or at the apices of the thalline lobes. Soralia are present in 

 Parmelia onoiigeotii, P. amhigtia, P. duhia, and P. reddenda. In 

 Physcia grisea the margin of the thallus is sorediate. 



{k) Platysma (Cetraria) 1, 2, 4, 5 and sometimes 7. 



(Z) Corticate and rhizinose beneath — having the lower surface of 

 the thallus formed of cells and with rhizinse. 



(?«) Placodium here refers only to Euplacodium of the Mono- 

 graph. P. xantlioliitum is leprose (or scurf-like) and sterile, whilst 

 P. fulgens has simple spores, but otherwise t\\Qj agree with the 

 chai'acters given in the key. 



{n) In some species of Pliyscia the lower cortex is imperfectly 

 cellular. The species of Pliyscia would nearly always be referred 

 here, except in the case of the ±fi'^^ticose species 1-3. 



{o) In laciniate plants the lacinise can only be seen under a lens 

 with a small magnifying power. In squamulose plants the width of 

 the squamules may approach 1 mm. but the squamulose character is 

 indistinctly shown. 



(^;) Collema 5-13. Zieptogium 18-20. 



(^) The th. is sometimes larger than indicated by the kev. 



\r) Leptogium 1-7, 9-12, 14-16, varieties of 20. 



(s) Besides the Psora section, other Lecideas (e. g. L. gagei, 

 Jj. coarctata, L. demissa,L. wallrothii, L. endomclcena, and L. nigro- 

 glomerata) have minutelv squamulose forms. 



(0 Bilimhia 1-4, 6-S, and 26. 



{it) Some Lecanoras, e. g. L. gangaleoides, L.frustiilosa. L. argo- 

 pholis, may have a similar subsquamulose appearance, but the spores 

 are simple. The three examples given have a yellow reaction with K. 



B. Thallus fruticose («) or cylindrical or iilamextous. 



1. Th. of long cylinders or of ±erect strap- 



shaped bodies, not gelatinous {h) 2. 



Th. of small or short cylinders, dark (often 



olive) and ^gelatinous (c) 14. 



Th. of minute filaments or c^dinders, dark 



(often olive) and ibgelatinous {d) 23. 



2. Th. of branching, ±entangled cylindrical 



(or semi-cylindrical) bodies, concolorous on 



all sides. Ap. parmelioid («?) 3. 



Th. of zbnpright cylindrical bodies (usu. little 



branched). Ap. various [f) 7. 



