DB. LAXTDEK LINDSAY ON AUTIIONIA MJELASPEUMELLA. 271 



the disk is paler or glaucous, resembling in this respect the apo- 

 thecia of the New Zealand Lecidea leucothalamia^ Nyl. (fig. 2, h). 

 Occasionally the apothecia of the Arthonia are subconvex and 

 immarginate, especially under moisture, when the disk swells and 

 absorbs for the time (fills or draws out) the rugose or wavy ex- 

 ciple or margin (figs. 2, 3, d). They also exhibit a tendency to 

 become difibrm, variously elongate or angular (fig. 2, e), re- 

 sembling the apothecia of various PatellaricPj e. g. P, atrata^ Fr. 

 as it occurs in my Herbarium from New Zealand. This elon- 

 gation or angularity appears to depend, on the one hand, on 

 the irregularities of, or pressure by, the fibres or rugae of the 

 wood on which the apothecia grow, and, on the other, on the 

 delicacy and tenuity of these apothecia themselves, Tlie hymenial 

 gelatine or the thecae give, with tincture of iodine, a very pale- 

 blue reaction in some cases (fig. 4, a) ; but generally there is no 

 reaction or coloration at all *. The paraphyses (fig. 4, J) are 

 very delicate and not easily seen, exhibiting themselves generally 

 as a confused yellowish mass of filiform tubules, without coloured 

 or clavate heads. But in other cases, especially when old, they 

 become subdiscrete, and are then seen to possess bulging or 

 knobbed heads (fig. 4, e). The thecse (a) are short, obovate, 

 and 8-spored, having the saccate character of those common in 

 the genus Arthonia, about '0012 inch long, and '0003 to -00045 

 broad. The spores (fig. 5) are brown, 1-septate, soleasform (that 

 is, wdth the upper half, or locule, shorter and broader than the 

 lower), arranged in the thecae with the broader end upwards 

 (fig. 4, a), very small, varying in length from '00030 to '00045, and 

 in breadth from -00012 to '00014. There are no spermogones ; 

 but their place seems to be taken by pycnides (fig. 2, 3, c), which 

 externally resemble the usual spermogones of Arthonia^ in being 

 very minute, black, punctiform conceptacles, mostly semiimmersed 

 in the wood, scattered among the apothecia, generally outside 

 the region occupied by them. The stylospores (fig. 6, a) are 

 about '0006 to '0009 long, and '00012 broad, and are the terminal 

 articulations of short, linear, jointed, sterigmata, of a bluish 

 tint (J). 



In systematic works I do not find any reference to pycnides in 

 the genus Arthonia. But in 1856-58 I not only found them in 



* It will be observed that my experience differs here Bomcwhat from that of 

 Mr. CJurrey. This may have arisen from rarious causes, such as the different 

 strengths of the preparations of iodme used, or the comparatiTe freshness or 

 age of the plant when examined. 



