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PACHYSTOMA THOMSONIANUM. 
[PLaTE 220.] 
Native of West Tropical Africa. 
Epiphytal. Pseudobulbs on a trailing rhizome, roundish depressed, sulcate, an 
inch in diameter, clothed with a deep green membrane, which later on becomes a 
brownish coat to the bulbs (tunicate). Leaves oblong-lanceolate, acuminate, mem- 
branaceous, solitary or in unequal pairs, the largest about six inches long, plicate, 
palish green. Peduncles radical, one or two from each bulb, six ‘to. eight inches 
high, slender, bearing from three to four flowers, green, with a few lanceolate 
loosely appressed brown bract-scales. Flowers rather large, stoutish, spreading, very 
remarkable for the form of their lip; sepals lanceolate acuminate, the dorsal larger, 
erect, one inch and three-quarters long, and half an inch wide, the lateral ones 
smaller, directed downwards, obliquely affixed to the deflexed connate base of the 
lip, white ; petals narrow lanceolate, about the same size as the lateral sepals, 
white; Lip fleshy, adnate to the foot of the column, incumbent, the front portion 
erect, suleate at the base, three-lobed, the middle lobe _ smaller, triangular, linear 
acuminate, with three streaks and edge of deep magenta-purple, the lateral lobes 
aa erect, conchoid or obtusely ovate or subquadrate, greenish, freely striate inside 
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with brown-red, from the presence of short minute brown papille, with which the 
whole surface of the lip and column is covered. Column clavate, arched, subterete 
m its free portion, green streaked with red-brown. 
_ Pacuystoma . THomsonranum, Reichenbach fil., in Gardeners’ Chronicle, N.s., 
XI, 582; Jd. Xenia Orchidacea, iii. t. 213; Gardeners’ Chronicle, n.s., xii., 623, 
627, figs. 102, 103; Id. xviii, 501, fig. 87; Botanical Magazine, t. 6471; Williams, 
Orchid-Grower’s Manual, 6 ed., 507, with figure. 
This is a small genus of Orchids consisting mostly of Tropical Asiatic species, 
‘9 single one only, which we here figure, being a native of Tropical Africa, This 
indeed, is the only one that has come under our notice which is worth cultivating. 
Pachystoma Thomsonianum, our present subject, is a very pretty and very curious 
warf-growing species, worthy of all the care that can be bestowed upon it. The 
“ecompanying illustration gives a good idea of the plant, which is very rare. For 
the opportunity of figuring it we are indebted to Sir Trevor Lawrence, Bart., MP. 
of Burford Lodge, Dorking, whose collection abounds in rare species and varieties of 
the Orchid family. 
Pachystoma Thomsonianum is, as we have said, a very pretty species, and 
fomes from Tropical Africa. It is allied to I fpsea, and produces its erect slender scapes 
from the base of the depressed globular furrowed pseudobulbs; these scapes bear each 
m three to four flowers, which measure about three inches across, the dorsal 
