63 
Dr Greville on two new Genera of Byssoidea. 
taining its lustre to the most remote ages, and capable of resist- 
ing the action of acids and other fluids ; so that the modern art 
of manufacturing pottery-ware may be materially improved, not 
only with regard to the forms and ornaments, but also the pre- 
paration and application of the materials, by a diligent and con- 
tinued examination of those very ancient vases. 
Art. IV. — On two new Genera of Byssoidece , and a New Spe- 
cies of Eurotium. By Robert Kaye Greville, LL. D. 
F. R. S. E., &c. 
CHiETOPSIS. Greville. 
gen. char. Fila minuta , continua , erecta , opaca , setformia , 
ha si ramulis hrevihus instruct a. Sporidia pellucida , nu- 
da, inter ramulos coacervata. 
Chsetopsis Wauchii. Greville. 
Spec • Char . 
Desc. — Fila minuta, gregaria, subconferta, erecta, rigidiuscula, 
continua, opaca, nigro-fusca, laevia, valde attenuata, ramu- 
lis acutis brevissimis erecto-patentibus, basin versus instruc- 
ta. Sporidia nuda, oblongo-cylindrica, uniloculata, pelluci- 
da, albido-grisea, ramulis coacervata. 
Hab. In ligno putrido, vere, prope Edinburgum. 
A singular little plant, not two lines in height, with the stem 
resembling the persistent Byssoidece , while the sporidia are like 
those which belong to the more evanescent groups. It there- 
fore stands as it were between the two great natural divisions of 
these plants. So very slender and attenuated is the stem, that 
it is scarcely visible, unless held in a favourable light, though it 
rises like a bristle above the whitish mass of sporidia, which do 
not occupy more than a fifth part of the entire length, and are 
always confined to the base. Under the microscope, the spori- 
dia appear to be perfectly naked ; and on being moistened se- 
parate in an instant, and prove very numerous. I am not ac- 
quainted with any genus which bears the least affinity to the 
subject of the present description. 
