422 PROCEEDINGS OF THE AMERICAN ACADEMY 



inent, minutely rugulose margin bordering the soon convex and at length 

 hemispherical, scabrous disk ; which is white within, and rests on a 

 thick black hypothecium. Spores middling-sized, rather pale-fusces- 

 cent, pretty regularly ellipsoid ; the two sporoblasts soon flattened or 

 as if halved, and constantly joined by a stout isthmus, which is crossed 

 by the well-defined dissepiment. Of the same group with L. myrio- 

 carpa, DC, Nyl. (Z. chloropolia, Fr.) ; but strikingly distinct in the 

 development and color of the thallus, the larger apothecia, and much 

 larger spores, in which the isthmus, often observable (as a transient 

 feature, Koerb. Syst. p. 436) in spores of this type {Buellia, De Not.) 

 appears to be constant. 



Professor Lovering and Dr. M. Wyman supported the opin- 

 ion of the majority of the Rumford Committee, that it is not 

 advisable to award the Rumford Medal to Mr. Ericsson for 

 improvements in the hot-air engine. 



Professor Horsford, in reply, further supported the claims 

 of Mr. Ericsson. 



Five hundred and eightli meeting. 



May 13, 1862. — Monthly Meeting. 



The President in the chair. 



Professor Peirce presented, in behalf of the author, a paper 

 On Certain Forms of Interpolation, by W. P. G. Bartlctt. 



Professor Lovering and Professor Winlock, on the one side, 

 and Professor Horsford on the other, continued the discus- 

 sion upon the merits of hot-air engines, with especial refer- 

 ence to that of Mr. Ericsson, and to the majority and minority 

 reports of the Rumford Committee upon the subject. 



Remarks relative to the course proper to be pursued by the 

 Academy in this regard were made by Messrs. Washburn, 

 C. Pickering, Agassiz, Peirce, A. Gray, and the President. 

 And the further consideration of the subject was postponed to 

 the Annual Meeting ensuing. 



