536 DR. LINDSAY ON NEW-ZEALAND LICHENS. 
Genus XX. PLACODIUM. 
Sp. 1. P. MURORUM, DC. var. miniatum, Hffm. | Linds. Spermog. 266, plate xy, 
figs. 1, 2.] 
On slaty trap, Shaw's Bay, the Nuggets, and Kapuwaka Creek, Finegand Station, 
Lower Clutha. Common on tale-slate, Otokia Bluff, Otago: abundant also on the 
trachytic rocks which form the banks of the Pukaki lake, North Shore, near the town 
of Auckland, as well as on the trachytic and other rocks which constitute the basis or 
bulk of Beeson's Island, Coromandel Harbour, Auckland: W. L. L. 
Genus XXI. Puacopsts, Nyl. 
Sp. I. P. cena, L. [Linds. Spermog. 261. | 
On basaltie rocks and boulders, Kaikorai Hill; Signal-hill, N.E. valley, Dunedin. 0n 
basaltic porphyry, Forbury Head, Dunedin. On basaltie rocks in the gullies of the 
Greenisland hills. On slaty trap and trap conglomerates, Ferry Bluff, Clutha ferry: 
apparently partial to basaltie rocks and stones, on which it is more or less common, and 
frequently in fruit, throughout the Greenisland and Saddle-hill district of Otago: W. L. L 
Often associated and apt to be confounded with P. perrugosa, Nyl. (L. N. Z. 250; Linds. 
Obs. Otago Lich. and Fungi, p. 415, plate xxix. fig. 17), with which it is at least closely 
allied. 
Apothecia large and very irregular in form, frequently with a wavy or plicate outline 
or surface. Thallus granulose or subpulverulent, the granules or isidia sometimes over 
growing the apothecia; sometimes tartareous, thick and whitish, approaching Lecanora 
tartarea or L. parella; sometimes assuming a pale yellow tint. 
In herbarium Kew occur North-Island specimens (Colenso, no. 4740), on water-worm 
pebbles, sterile : which are identical apparently with the same species, gathered by myself 
: on the banks of the Caledonian Canal. 
Placopsis is the latest secession from Squamaria or Lecanora, as Parmeliopsis is from 
Parmelia. I cannot agree with Nylander as to the necessity for such dissociation, pre 
ferring to regard them as groups of an old genus rather than themselves the types of new 
genera. The passage genera between Parmelia and Lecanora appear to me to be unne 
cessarily numerous (especially Pyzine, Psoroma, Pannaria, Coccocarpia, Amphilom 
Squamaria, Placodium, Placopsis, which, I think, might be reduced, and united, with 
great advantage to classification). 
P. gelida is one of many lichens recorded in Fl. N. Z. as a North-Island species on 
simply because, at the date of its publication (1855), the lichens of the South Island had 
not been (at least to the same extent) collected and examined.* New-Zealand sp% 
cimens generally agree in aspect and character with those of Highland ( Scotch) repre 
sentatives of the same species. 
* Compare remarks under head Verrucaria. 
