324 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
under potash. In Kikerton arctica, potash and iodine develop no colour-reaction on 
either cortical or medullary tissues. A few octahedral erystals of oxalate of lime were 
met with in the thallus. 
In the Kikerton plant, the sporidia are simple, spherical, colourless, about 00015" in 
diameter, with double contour, or granular, or marked with a central nuclear point. Asci 
blue with iodine. The spermogonia are distinct under the lens, scattered sparingly about 
the angles of the podetia, as in madreporiformis. Spermatia straight rods on delicate 
arthro-sterigmata, resembling those of many Parmelie * (e. g. P. perlata, physodes, and 
encausta), the sterigmata being associated with hypertrophied, sterile filaments, similar to 
those that also occur in the genus Parmelia* (e. g. P. tiliacea, acetabulum, and perforata). 
Basal cellular tissue brown. Nylander says that the spermogonia of arctica have not 
yet been seen (Synopsis, p. 286) ; and Tuckerman t also describes them as ** unknown." 
Nevertheless I figured and described them in my * Memoir on Spermogonia ’} published 
in 1859, the date of Tuckerman's paper being 1862, and of Nylander’s ‘Synopsis’ (vol. i.) 
1858-1860. 
What I figure differ, however, from those since figured by Leighton$. It does 
not follow that the plants examined in this case by Leighton and myself were 
different species or genera; for not only may the same object appear under different 
aspects to different observers, but I have already pointed out that the same species of 
lichens not unfrequently possess two or more forms of spermogonia, spermatia, and 
sterigmata |. The spermogonial contents would appear to be equally variable in madre- 
poriformis; for the sterigmata and spermatia figured by Nylander (Synopsis pl. viii. 
fig. 23) are very different from those figured by myself (Mem. Spermog. pl. vi. fig. 22). 
Dufourea madreporiformis, in Scheerer's Exs. 85, bears spermogonia only. They are 
more frequently irregular, and confluent or deformed, than those of arctica; otherwise 
they are alike. Tuckerman admits the “ obvious affinity " of D. madreporiformis and 
Dactylina arctica, though he also refers to their **equally obvious differences " (p. 397). 
He regards the two as * mediated " by Dactylina ramulosa, Hook., which is evidently 
quite our Kikerton plant. He refers madreporiformis (and properly, I think) to the 
genus Dactylina (p. 398). The Kikerton Dactylina and Schærer’s Dufourea (Exs. 85) 
appear to me to be the same plant. 
Genus 11. NEPHROMA. 
l. N. arcticum, L.—Godhavn. Abundant; in large masses, but without apothecia. 
In West Greenland, where it ascends to 300 feet above the sea, Vahl says it is always 
sterile. Thallus not tomentose; frequently white below, especially peripherally. At one 
* Vide the Author's * Mem. Spermog.' pp: 291-3, plates xi. & xii. and Explanations thereof. 
T “Observations on North-American Lichens,” Proceed. of American Academy of Arts and Sciences for April 22, 
‘1862, p. 396. 
+ Page 133, plate vi. fig. 23. 
$ “On the Lichens collected by Sir John Richardson in Arctic America,” Journal of Linnean Society, vol. ix. 
Botany, p. 192, plate ii. figs. 16, 17. 
|| “On Polymorphism in the Fructification of Lichens,” Quart. Journal of Microscopical Science, Jan. 1868 ; or 
Report of the British Association, 1867, p. 89. 
