OF ARTS AND SCIENCES. 285 



and at length convex, black, the margin evanescent. Thallus filamen- 

 tous, not gelatinous. 



E. puhescens, Fr. Thallus decumbent, softish, terete, black, the 

 branches entangled, capillaceous ; apothecia of the same color. Fr. 

 Fl. Scan. p. 294. Cornicularia, Ach. — /5. JibriUosa, Ach. ; thallus 

 obscurely fuscous, smoothish, very delicate, branched, somewhat hir- 

 sute with numerous, flexuous, branched, subclavate fibres. Cornicula- 

 ria puhescens, var. fbrillosa, Ach. Syn. p. 302. 



Rocks and stones; — «, in alpine districts. Greenland, Dill. White 

 Mountains. — /5, North America, Ach. 



Professor Peirce communicated to the Academy Mr. Sears 

 C. Walker's elliptic elements of Neptmie. 



"71 = 48 21 2.93 ) ^^^^ equinox, Jan. 1, 1847. 



$2 = 130 4 35.03 i 



i = 1 46 59.54. 



e = 0.00S57741. 



fl = 21".55448. 



M — 328° 31' 56".36, mean noon, Greenwich, Jan. 1, 1847. 



T = 164.6181 tropical years. 



" The normal elliptic places of Neptune, derived from the discus- 

 sion of 689 observations, European and American (including the two 

 ancient observations of Lalande), were as follows: — 



I. — 18864 = Rlay 9th, 1795, 215 48 /gS — 44".l (r — 30.28778). 

 II. — 134 = Aug. 20th, 1846, 326 45 30.83 — 1.2 (r' — 29.99256). 



III. — 55 = Nov. 7th, 1846, 327 13 58.57 — 227.6 (r" — 29.99256). , 



IV. 4- 95 = April6th, 1847, 328 8 0.67 + 163.8 (r'" — 29.99256). 

 V. + 233 = Aug. 20th, 1847, 328 57 44.39 + 1.0 (r"" - 29.99256). 



" These elliptic places were derived from Neptune's places in the 

 instantaneous orbit, by the subtraction of the effect of the perturbations 

 of all the other planets, as communicated to Mr. Walker by Professor 

 Peirce in November last. 



" The expressions for the heliocentric coordinates are, — 



a; = [9.9998769] r sin. {v + 138 21 52.13) m. eq. Jan. 1, 1847. 

 y = [9.9662265] r sin. (u + 48 55 27.32). 

 z = [9.5800962] r sin. (u + 45 2 37.90). 



