a New Mineral Species found in Glcnco. 221 



put into my hands a specimen of the rock containing small 

 masses of Withamite, which lie had carefully polished. The 

 high lustre of the Withamite was thus rendered obvious to 

 the dullest eye; but I was surprised to observe, that the pale 

 red mineral which almost always separates the Withamite 

 from the trap-rock, was quite inferior in lustre to it. I there- 

 fore examined the action of these three surfaces upon lio-ht 

 when reduced by the opposite action of oil of cassia. When 

 the image of the sun was reflected from the surface of the 

 rock, the light was faint, and of a pale blue colour; — when it 

 was reflected from the surface of the Withamite, it was bright 

 and of an orange colour ; but when it was reflected from the 

 surface of the pale red substance round the Withamite, the 

 image was scarcely visible. Hence we conclude, that this 

 second substance, which seems to be a new mineral, has the 

 same refractive power as oil of cassia, and that in its action 

 upon light it comports itself like topaz from Brazil. 



Upon mentioning this experiment to Mr Haidinger, he ex- 

 amined the pale red substance, and considers it as havinw 

 some resemblance to Saussurite. 



Art. IX. — On the Genus Hookeria of Smith, of the or- 

 der Musci. By W. J. Hooker, LL.D. F.R.S. &e. &c. 

 Regius Professor of Botany in the University of Glasgow ; 

 and R. K. Greville, LL.D. F.R.S.E. &c. &c. Com- 

 municated by the Authors. 



Hookeria. 



Gen. Char. — Seta lateralis. Peristomium duplex, ext. e den. 

 tibus sedecim ; int. membrana 16-iaciniata, nunc ciliis 

 alternantibus. Calyptra mitriformis. 



The genus Hookeria was established by Sir J. E. Smith, in a 

 memoir published during the year 1808, in the Transactions 

 of the Linnean Society, vol. ix. and was defined thereby cha- 

 racters, which, with very slight exceptions, we have here a- 

 dopted. The well-known moss Hypnum Jucens, is to be con- 

 sidered as the type of the genus ; to this, Smith added H qita- 

 drifarium, the Leskea peunata of Labillardiere, L. JUiculifor- 

 viis, Hedwig, L. tamariscina, L. rotulata of the same author, 

 Hookeria jlabellata, IT. Arbuscula, L.jUxilu of Hedwig, and 



