212 DR. LINDSAY ON THE SPERMOGONES AND 
base, about 3055 to 1550 long. The spermatia are subellipsoid and very small, zoo 
long, and 45:455 broad. The character of the spermogones and spermatia here quite 
. agrees with the drawings and descriptions of Tulasne*. This is one of many cases in 
which it will probably be necessary to make many sections and examinations before the 
student succeeds in discovering the spermogones. 
Specimen 2. Isidioid forms = Isidiwm corallinum, Ach. pr. p., in the Hookerian 
herbarium, Kew: Glen Callater, Braemar: Gardiner, July 1844. The spermogones con- 
stitute greenish dots on the apices of the thalline isidia. They are inconspicuous, wholly 
immersed, generally round, but sometimes irregular in outline (e. g. chink-like or angular). 
The spermatia are straight rods, ¿755 long, aud 35505 broad, seated on simple, digitate 
sterigmata, about 3555 to vogo long. I had long and repeatedly looked for spermo- 
gones in the brown papillæ topping the pillars or cushions that constitute this Zsidium, 
but hitherto in vain. 
Specimen 3. Other isidioid forms=TJsidiwm paradoxum of the * Lichenographia Bri- 
tannica ' (p. 97)— Lichen lacteus, Lich. Brit. (p. 69), in the Kew herbarium. The isidia, 
like those of J. corallinum, are tipped with brownish or greenish points, which, in one 
case at least, proved to be spermogones. The plant in which I found them is labelled 
** Specimen sent by Mr. Dickson.” : ; 
Specimen 4. Isidioid forms= Lichen dactylinus, Ach., in the Kew herbarium : labelled 
as from Dr. Scott, 1802, and as having been examined by D. T. (Dawson Turner). 
The thallus is pale brownish-yellow, and very irregular. Associated with isidia, it bears 
bodies resembling old or deformed apothecia, the disk a mere round pointed chink, the 
border very rugose and thickened. These are spermogones, immersed, opening by an ir- 
regular ostiole. The Hoc are straight rods, 3555 long and 5515 
simple sterigmata about 305 to 5560 long. Both spermatia and sterigmata are iden- 
tical, save as to size, with those described in specimen 2. 
It is always extremely difficult to assign supposed species of the pseudo-genus Zsidium 
to the Lecanore, of which they would appear, nevertheless, sometimes to constitute 
mere isidioid conditions. J. corallinum would seem to be at least partly referable to L. 
parella. According to its sporidia, which I found in a specimen from Miss Hutchins, in 
the Kew herbarium, J. paradoxum is probably referable either to parella or tartarea. 
Lichen dactylinus (the specific name, assigned apparently by Turner) may be conveni- 
ently considered in connexion with other Zsidia, though not belonging perhaps to parella. 
An additional reason for such association is to be found in the similarity of its spermatia 
and sterigmata to those of J. corallinam. 
Species 2. L. TARTAREA, Ach. 
Specimen 1. Var. frigide, Ben MacDhui, Braemar: August 1856. W. L. L. No 
apothecia: thalline warts consist of spermogones only. The thallus is very white and 
smooth, coating moss and earth, bearing an abundant series of distinct, large, ir- 
* “Mémoire pour servir à l'histoire organographique et physiologique des Lichens," Ann. des Sciences Nat., 
Botanique, 3d ser., vol. xvii. p. 182, plate 16. f. 18, 19. 
