321 
ON THE GEOGRAPHICAL DISTRIBUTION OF THE 
EQUISETACER. 
By J. MILDE, Pu.D. 
The first, and as yet only attempt, to enumerate and describe all the 
known members of the Natural Order Eguisetacee was made in 1822, 
in all essential characters, ought still to be rega 
Species if found in two different continents. In the Equiseta crypto- 
pora (E. hiemalia, auctor.) he laid too much stress upon the cir- 
cumstance whether the two rows of stomata were arranged in two 
lines instead of in one line. This deviation alone induced him some- 
times to make a new species. On the other hand, he neglected the 
most important points, viz. the form of the vagina and the carine 
and valleculee caulines of the foliola vaginarum. To give only one 
instance of his way of treating the subject, I may mention that the 
Well-known Æ. pratense, Ehr., is enumerated in three different places, 
as E. arvense, A, triquetrum, secondly as Z. umbrosum, Meyer, and 
thirdly, as E. pratense, Ehr. It should be added that specimens of 
z. pratense, Ehr., are preserved in Vaucher’s herbarium ; some labelled 
by Vaucher’s own. hand Æ. arvense, A, triquetrum, others E. umbrosum, 
er. The materials at Vaucher's disposal were rather scanty, as is 
evident from his monograph, and from an examination of Vaucher’s her- 
barium, which has passed into the hands of M. Alphonse de Candolle, 
a * Mémoires de la Société de Physique et d'Histoire Naturelle de Genève, vol. i. 
Part ii.; Geneva, Paris, 1822. 
OL. I. Y 
