Description of two new species of Opuntia. 467 
tached as part of the ovarium, which, inceed, it appears to be, when 
seen from the outside of the flower, but in a transverse section 
(Fig. c.) is evidently prolonged above it. 
I have named this interesting Cactus after my friend C. Darwin, 
Esq. who has recently returned to England, after a five years ab- 
sence, on board his H. M. S. Beagle, whilst she was employed in 
surveying the southernmost parts of South America. The speci- 
men figured was gathered in the month of January, at Port Desire, 
lat. 47- S. in Patagonia. He recollects also to have seen the same 
plant in flower as far south as Port St Julian in lat. 49. S. It is 
a small species growing close to the ground on arid gravelly plains, 
at no great distance from the sea. The flowers had one day arrest^ 
ed his attention by the great irritability which their stamens mani- 
fested upon his inserting a piece of straw into the tube, when they 
immediately collapsed round the pistil, and the segments of the pe- 
rianth soon after closed also. He had intended to procure fresh 
specimens on the following day, and returned to the ship with the 
one now figured, but unfortunately she sailed immediately after- 
wards, and he was prevented from obtaining any more. The geo- 
graphical position of this species is beyond the limits hitherto as- 
signed to any of the order, which are not recorded as growing much 
south of the tropic of Capricorn. The climate is remarkably dry 
and clear,1hot in summer, but with sharp frosts during the winter 
nights. He found Cacti both abundant and of a large size, a little 
further to the north at Rio-Negro in latitude 41. S. 
Sp. 2. Opuntia galapageia. articulis compressis (saltern junioribus) 
obovato-rotundis, aculeis setiformibus, longis, penicillatim dispo- 
sitis, lanugine supra ovarium densa. 
Plate XIV. Fig. 2. 
I am also indebted to Mr Darwin for this second Cactus, of which 
he brought home in a dry state the specimens here figured. He 
found it at the Galapagos islands, where it attains to the form of a 
tree, averaging from six to ten feet high, and about a foot in diame- 
ter, perfectly cylindrical or very slightly tapering. The bark is 
pale-coloured, and in old trees hangs in a ragged manner upon the 
trunk, which is covered with very strong sharp spines, five to ten of 
which are set in each fasciculus, in a radiatory manner. From the 
summit of the trunk numerous branches spread on all sides, somewhat 
in the manner represented by Fig. /., taken from a very rude sketch 
of Mr Darwin's. He states these branches to be composed of com- 
pressed, rounded, oval articulations, each of which is about one foot 
in length, wholly without the true spines found on the trunk ; but 
