axe PS yom hs 
Excerpta Botanica. 257 
Two specimens of this beautiful insect were brought from Monte 
Video by Mr. Darwin. 
Baripus rivalis (Molops rivalis, Germar), Dejean. Species Gen. 
des Col,, vol. iii. p. 25. 
Two specimens of this species from Monte Video, and one speci- 
men from Maldonado La Plata, occur in the collection. 
XXIX.—Excerpta Botanica, or abridged Extracts translated 
From the Foreign Journals, illustrative of, or connected with, 
the Botany of Great Britain. By W. A. LeicutTon, Esq., 
B.A., F.B.S.E., &c. 
No. 3. On the Structure of the Hairs on the Pericarp of cer- 
tain Plants. By M. Decaisnu. (Ann. des Sc. Nat. n.s. 
xii. p. 251.) 
One of the characters of the genus Ruckeria is, that of 
having the pericarp covered with papillae. These papilla, 
when attentively examined in a dry state, are found to be of 
a club-shaped form, of a pearly appearance, and with a lon- 
gitudinal line dividing them into two equal portions. Their 
‘base is dilated or curved, in the different species, so as to rest 
upon one of the cellules of the epidermis, in the organisation 
of which there is nothing unusual. On placing some of these 
papillz or hairs in a drop of water, we immediately see them 
Separate at the apex into two lips, and thence emit two tubes 
{boyaux) of a mucilaginous substance, which issues forth 
like wires spirally unrolling themselves, twisting about on 
themselves many times, and finally greatly exceeding in 
length the hairs into which they were apparently thrust. - 
These tubes are apparently formed by a very considerable 
number of filaments, united and placed one upon the other, 
in the manner of a skein of thread, of which the pieces adhered 
together by means of some gummy substance. When these 
hairs are moistened, we distinguish through their parietes in 
each of the two lateral moieties, two bodies more opake, at= 
tenuated at both ends, and exhibiting striz arranged in a 
regular series, but changing their direction at certain intervals. 
If the hair, instead of adhering to the pericarp, as in the 
preceding example, is broken off at the base, the emission of 
the tubes takes place at that extremity, and the two are then 
seen to descend slowly, and to proceed parallel to each other 
for a short time in unrolling themselves, but afterwards to 
curve and twist one around the other in an irregular manner. 
Sometimes when the hair is not broken off, the tube issues 
forth from the side, and almost constantly about the middle, 
Ann. & Mag. Nat. Hist. Dec. 1840. 8 
