Dr. W. Nylander on Lichens. 105 



He now makes known those which he has recently discovered 

 on the lower surface of the thallus, and most frequently on the 

 fuscous tomentose nerves of Peltidea venosa. These cephalodia 

 are granular, cartilaginous, glaucous or glauco-cinereous (at 

 length becoming dark or blackish), small (commonly 0*2-0*5 

 millim. broad), superficial, subglobose or somewhat depressed, 

 not unfrequently clustered. They contain granula gonima, of 

 moderate size and moniliform, in a thin cellular texture. 



GONIMIA, LEPTOGONIDIA, OR GONIDIMIA. 



Dr. Nylander (/. c.) suggests that it may be advisable to call 

 the granula gonima by the term " gonimia," to distinguish them 

 from true gonidia. Perhaps, also, the gonidia of peculiar type 

 which are observable in Peltidei, Solorince, Nephroma expallidum, 

 and which are of small size and furnished with a thin cellular 

 wall, may deserve a distinct name, which he proposes to be 

 " leptogonidia" or " gonidimia," 



CLADONIA, CLADINA. 



Dr. Nylander (in Flora, 1866, p. 178) proposes to divide the 

 genus Cladonia thus : — 



Those species which have a thallus leafy or squamaceo-foliolose 

 at the base, and podetia (with a cortex partially split up and 

 powdery) often more or less furnished with leaflets or scales, 

 and still oftener more or less scyphophorous, he retains in the 

 genus Cladonia. 



Those species which have a leafless thallus, podetia commonly 

 without scyphi, branched, the branches sharply pointed, a cortex 

 not splitting up, and powdery (although sometimes evanescent, 

 and thus denuding the subarachnoid stratum medullare), he 

 comprises in a new genus, Cladina. In this he arranges C.rangi- 

 ferina, peltasta, uncialis (et amaurocroea), medusina, candelabrum, 

 gorgonea, Salzmanni, divaricata, leporina, aggregata, retipora, 

 schizopora, and perhaps also papillaria. 



Cladonia furcata and its allies approach to Cladina, but differ 

 by possessing leaflets. 



SPERMOGONIA. 



To show the value of the spermogonia as a distinctive cha- 

 racter. Dr. Nylander states (/. c. p. 181), "Platysma subperlatum, 

 spermogoniis neglectis dignosci fere non potest a Parmelia 

 latissima ; Platysma commixtum vix nisi spermatiis distat a Pla- 

 tysmate Fahlunensi; Physcia adglutinata similiter distincta a 

 Physcia obscura, quarum (spermatiis non examinatis) ante juncta 

 fuit ut varietas." 



Ann. ^ Mag. N. Hist. Ser. 3. Vol. xyiii. 8 



