SCHIZOMA.] 



39 



towards the extremities. la Journ. Bot. 1874, 1. c., it was observed that 

 this species probably constituted a separate genus, though, as neither form 

 of fructification was then known, it might be retained as an anomalous 

 section of Collema. I have since detected the spermogones in Great 

 Britain, and I hope the apothecia may be also discovered. The de- 

 scription of the thallus of Collema radiatum Somm. (possibly an Ompha- 

 laria) and its habitat given by Sommerfelt, Lapp. p. 121, as well as the 

 account of its internal structure and of the spermogones given by Fr. fil., 

 Lick. Arct. p. 288, do not at all correspond with our plant ; the two can- 

 not be identical. On the thallus is rarely seen a parasitic fungus, viz. 

 Sphccria schizomatis Cromb., which must not be mistaken for the apothecia. 



Hob. On decayed mosses and the ground in crevices of rocks in alpine 

 places. Distr. fcxtremely local, being confined apparently to one or two 

 of the S. Grampians, Scotland. B.M. : Ben Lawers and Craig Calliach, 

 Perthshire. 



14. COLLEMA Wigg. Prim. Fl. Hols. (1780) p. 89; Nyl. 

 Mem. Soc. Sc. Nat. Cherb. iii. (1855) p. 164. Thallus usually 

 orbicular or suborbicular, membranaceo-lobed, very rarely squamu- 

 lose or granulose ; gonimia moniliform, cortical layer not discrete. 

 Apothecia lecanorine ; spores 8nae, simple or generally multilo- 

 cular, colourless ; hymenial gelatine usually bluish, rarely wine-red 

 with iodine. Spermogones more or less immersed, sterigmata 

 shortly articulate, rarely simple ; spermatia straight, obtusely in- 

 crassate at either apex. 



As now limited, this genus is more compact than formerly, though it 

 still includes several species, diverse in thallus and fructification, as 

 will be seen from the following sections. These differences, however, 

 are not of sufficient importance to warrant its division into several genera. 



In various species a thin section of the thallus, when dry, becomes 

 reddish or blood-red with iodine, in consequence, as Nylander observes, 

 of the gonimia being so coloured. In the species in which the spermo- 

 gones have been detected, except in those belonging to Section A, the 

 spermatia are identical in size, viz. 0,0035-0,0040 mm. long, 0,0007 mm. 

 thick, or vary so slightly that the difference is scarcely perceptible. There 

 is every reason to believe that some Nostocs are undeveloped states of 

 different spacies of this and perhaps also of the following genus. 



A. LEMPHOLEHMA (Koerb. 

 Syst. Lich. (1855) p. 400). 

 Thallus thinnish, dif- 

 form ; gonimic granules 

 moniliform. Apothecia 

 innate ; spores simple ; 

 spermogones with simple 

 sterigmata. 



a. Hymenial gelatine wine-red 



with iodine. 



1. C. chalazanum Ach. Lich. 

 Univ. (1810) p. 630. Thallus 

 pulvinate, thinnish, difformi- 

 lobate or laciniate, crenulato- 



cP 



Fig. 10. 



Collema myriococcum Ach. a. Section 

 of an apothecium, X 30. b. Two 

 thecae arid a paraphysis, X 350. c. Two 

 spores, X 500. d, Sterigmata, and 

 e, spermatia, X 500. 



