452 DR LAUDER LINDSAY ON THE 



the centre of the group the spermogones, which are small, spherical, frequently 

 confluent ; the walls thick and black ; the spermatia straight, very slender, and 

 about -00012" long. 



A. Nylander exs. Covering the disk of the apothecia (the larger and more 

 mature) of Sticta pulmonacea, Ach. Thecce, pale blue or dirty purple with 

 iodine; a fact of some significance in relation to the question, whether the 

 genus Celidium is a Lichen or a Fungus ; 8-spored ; 0023" long, -00066" broad. 

 Spores fusiform or ellipsoid ; somewhat variable as to form and size ; colourless ; 

 3-septate ; sometimes not exhibiting the epispore in the young state ; sometimes 

 seen in process of germination ; in the old state brown and obscurely granular ; 



00066" long, 00025" to -00016" broad. Tips of paraphyses deep brown. 



B. Sch^erer exs. 550, sub nom. B. pleurocarpa, Ach , of S. pulmonacea, Ach. 

 Here the paraphyses are extremely indistinct ; the thecce are 8-spored, and 0020" 

 long, 00066" broad. Spores 00083" to 00066" long, -00025" broad; 3-septate; 

 pale yellow ; ellipsoid, sometimes sub-pyriform ; sometimes exhibiting bulgings 

 of the epispore opposite the septa. 



Scattered irregularly over the thallus are numerous maculae or papillae of 

 variable size and appearance, wholly devoid of reproductive structure, and 

 evidently partly rudimentary or protothalline, partly degenerate ; but apparently 

 referable to the parasitic Celidium, whose sporiferous perithecia (perfect or 

 fertile condition) are to be found only on the apothecia of the Sticta. The 

 papillae resemble young lecidiiform apothecia, or Verrucarice, or spermogones. 

 The maculae are sometimes sufficiently raised or convex, and regular in 

 their outline (spherical), to approach in character some forms of Abrothallus or 

 certain lecidiiform Arthonioe. Both papillae and maculae are blackish brown of 

 various shades, and are isolated and somewhat regular in form, or confluent and 

 difform; in the latter case frequently with ragged margin. The flat, thin (rudi- 

 mentary) maculae are sometimes irregularly stellate and Arthonioid ; sometimes 

 sub-dendritic ; seldom confluent ; sometimes elongated, or sub-oblong, and with 

 a general Fungoid aspect ; generally, with the other forms, seated on the thalline 

 rugae. 



In Hepp's exs. 590, the Celidium of the apothecia (of all sizes) of S. pulmonacea 

 is accompanied with maculae on the thallus, similar to those just described, and, 

 as usual, without reproductive structure. Similar Celidia* whether in their 

 fertile and perfect — or, as is more generally the case, in their sterile and imper- 

 fect—state, occur on a large proportion of the Stictce ; sometimes on the apothecia 

 or thallus, or both (as in S. scrobiculata, Ach , and S. Freycinetii, Del.); sometimes 

 on the verrucose or tuberculose thalline cephalodia (as in Ricasolia corrosa, Ach. 

 Nyl. Syn. 372): in which latter case the parasite is analogous to Abrothallus 



* Yet apparently undescribed. 



