DR. LINDSAY ON WEST-GREENLAND LICHENS. 325 
point, in one of the Godhavn specimens, spermogonia occur. They have the aspect of 
young apothecia, with the colour of the disk of Lecanora tartarea. They are evident 
under the lens only when the thallus is moistened. They then appear as marginal, irre- 
gular, buff-coloured tubercles, isolated or grouped, becoming subgelatinous under moist- 
ture. Sometimes they are confluent, in large compound, irregular masses, having quite 
an apothecioid character. In all their forms the spermatia are the same—simple, spherical 
atomic, in myriads, about 00015" to :00020” long and :00060" to 00075" broad. The 
sterigmata are indistinct. 
N. arcticum is sometimes confounded with forms of certain of the Peltideæ : e. g. in the 
Kew Herbarium, one of two specimens labelled P. horizontalis, from Canada (Shepherd), is 
this Nephroma. The distinction of Nephroma and Nephromium as separate genera 
appears to me a most artificial and unnecessary one. 
Gen. 12. PELTIGERA *. 
. l. P. apthosa, Ach.—Egedesminde. Sterile, as it generally is. In Herb. Kew. it 
occurs from Disco (Lyall, 1854). 
2. P. canina, Hffm.—Lyngemarken. In fruit and pycnidiferous. The thallus is that of 
canina; but the sporidia exhibit greater variety of form and size than is common in that 
or any other species of the genus; the upper surface of the thallus is sometimes lurid-grey 
(dark lead-colour), becoming darker when moistened, and covered with a sparing white 
pruina; the under surface is very fibrillose-rhizinose, of the usual whitish colour, with 
buff or cream-coloured veinlets and rootlets. The upper surface is occasionally the site of 
a black, papilleeform, very minute, semiimmersed parasite, which shows, however, no 
specific structure. ; 
The sporidia of the Peltigera are (apparently) normally 4-locular : but in the young 
state they are simple, or 2-locular, in the former case frequently granular. They are 
usually fusiform or broadly ellipsoid, but sometimes pyriform, oval, or even linear-oblong. 
Though generally straight, they are sometimes curved. Their character varies greatly, 
even in the same section of one apothecium, under the field of the microscope, at the same 
moment—the variations relating equally to form, size, and structure. They are invariably 
colourless; usually about :0009" to 0012" long and :0003” broad, associated with large 
numbers of oil globules of all sizes. Sometimes, instead of distinct loculi, they contain 
one or more large cellular nuclei. Hymenial gelatine pale blue with iodine. Tips of 
paraphyses pale brown. 
. Pyenidia occur as marginal brown buttons or warts, filled with myriads of stylospores, 
all very delicately muco-granular or shaded, very variable in size, the average about 
00027” to -00030" long and 00009” to 00015” broad ; their diameter, when subspherical, 
:00022". Their form is oblong-oval, pyriform, or irregularly angular, many of them 
resembling pus or tubercle corpuscles; their outline is rendered more distinct by iodine, 
- * The old Acharian genus Peltidea is now generally known (for what reason I am not aware) as Peltigera. In a 
letter to me, of date February 1866, Nylander speaks of the “ genre Peltidea qui diffère par ses gonidies (qui rendent 
leur thalle à l'état humide d'un beau vert) des Peltigera (dont le thalle à l'état humide devient foncé"). To Peltidea 
he refers venosa, Ach. 
