OP ARTS AND SCIENCES : APRIL 12, 1864. 287 



lichen easily reminds one of Acarospora molyhdina, v. microcyclos, 

 Walil. It belongs to the group represented by Verrucuria (Stauro- 

 thele) umhrina, Fr., but is distinguished from that and other allied 

 lichens by the thallus. — Dedicated to the discoverer, A. T. Drura- 

 mond, Esq., of the Botanical Society of Canada, author of a catalogue 

 of the plants of Canada, now in preparation. 



Addenda. 



Placodium coralloides, sp. nov. : thallo fruticuloso cartilagineo 

 decumbente vitellino-flavo ramis teretibus subdichotome divisis nodulo- 

 sis obtusis basi nigricantibus ; apotheciis mediocribus lateralibus podi- 

 cellato-elevatis zeorinis plano-convexis disco saturatiori margine tenui 

 integro instructo, thallino mox excluso. Sp. in thecis ventricosis octo- 

 naj, oblongo-elhpsoidese oblongteque, diblastre sporobl. approximatis, 

 diam. dein 2^-3° longiores. California, Herb. Gray, growing prob- 

 ably upon rocks. Thallus solid. Thalline margin of the apothecia 

 commonly excluded. Spores comparable rather with those of P. 

 vitellinum, more or less oblong, rarely a little oblique, a thin dissepi- 

 ment sometimes observable, but no trace of an isthmus. Paraphyses 

 thickened and yellowish above. The genus is here taken in the sense 

 of Dr. Stitzenberger (Beitr. z. Flechtensyst. in loco), and includes 

 merely crustaceous as well as effigurate types, which are well brought 

 together by the pecuHar differentiation of the spores, and, with some 

 exceptions, by the colors. 



Placodium erythranthdm. Lecanora, Tuckerm. Obs. Lich. 

 1. c. 4, p. 402. Nyl. in Prodr. Fl. N. Granat., Lich. p. 28. In Cuba. 



Placodium diphasium. Lecanora, Tuckerm. Suppl. I. 1. c. p. 

 426. In Texas. 



Placodium camptidium. Lecanora, Tuckerm. Obs. Lich. I. c. 4, 

 p. 403. In Southern Pennsylvania, and southward. 



Placodium Floridanum. Lecanora, Tuckerm. Obs. Lich. 1. c. 4, 

 p. 402. In Florida and Texas. 



