176 PROCEEDINGS OF THE AMERICAN ACADEMY 



noplacce vix distinguendis nisi sporis minoribus longit. circ. OjOiG-SG""™ , 

 crassit. 0,023-2G™™-. 



With the last, at Sholl Bay, and also, on bark, in the Galapagos Is- 

 lands, ^ey. T.Hill (Hassler exp. 1872). The material does not enable 

 me to explain the true relation of this lichen to that immediately pre- 

 ceding. With so much agreement in the fruit, the differences in the 

 tliallus are startling ; while yet specimens of each, well covered with 

 papillae, may be supposed at sight the same. 



Pertusaria ambigens : thallo cartilagiueo la3vigato subinde rugoso- 

 veriucoso glaucescente ; apotheciis lecauorinis (latit. 0,6-1,8™"'') sessili- 

 bus vel subelevatis 1-2-tlialamis, margine thallino lacero-subcrenato 

 demum repetito-duplicato discum planum viridi-Ciesium cingente. 

 Sporaj octonce, ellipsoideai, simplices, incolores, 0,01 7-23"""-, longoe, 

 0,008-1 2"""' crassfe ; paraphysibus capillaribus. Lecanora ambigens, 

 Nyl. Eiium. Gen. Lich. p. 113, and Prodr. Ft. Nov. Granat. p. 40, 

 not. 



On trunks, Oregon, at 49° N. lat., Dr. Lyall ; and elsewhere in the 

 same country, E. Hall. The lichen does not differ from a Cape of 

 Good Hope plant {Zeylier in herb. Sonder), also on bark, which is, 

 without doubt, what Nylander has described (Prodr. N. Granat.) irom. 

 the same herbarium. And, so far as appears, it fully agrees also with 

 a rock lichen collected by Mr. AVright at the Cape, and long since de- 

 termined by Nylander as his Lecanora ambigens. The spore-features 

 vary somewhat from the Pertusaria type, and appear to have influ- 

 enced the first describer in excluding the lichen from the genus to 

 which, however, he admits that it perhaps rather belongs. I can en- 

 tertain no doubt of this. Nothing illustrates so well the very peculiar 

 differentiatiou of the apothecia as forms associable more or less closely 

 with Pertusaria velata ; and sjiecimens of P. velata * rnidtijmncta are 

 before me which are hardly, at first sight, distinguishable but by the 

 spores. These apothecia (in the Oregon plant) present at length much 

 the a-p23earance in small of a pile of plates; the margin of the elevated 

 apothecium gaping horizontally into two, three, or more margins. 

 Spores enveloped in a halo in both the American and African lichens. 

 The spores of ours agree very well in size with my measurements of 

 the African {herb. Sonder), but Nylander (1. ( .) gives rather larger 

 figures, or 0,023-30""°- longit. and 0,010-11"^™- crassit. 



Pertusaria flavicunda, sp. nov. : thallo cartilagiueo laevigato 

 verrucoso-areolato pallide sulphureo, areolis ambitus radiose subconcre- 

 scentibus; apotheciis depresso-globosis (latit. 1-1,5 mm.) monothalamis, 

 ostiolo mox dilatato hymenium nigricantem pulvere lutuleuto adspersum 



