tions of the rostellum can be finely graduated together, 
even within the single tribe of Vandew ; and still more 
closely by commencing with the minute oval atom of mem- 
brane to which the caudicle of Orchis adheres, passing 
thence to Habenaria bifolia to that of H. chlorantha with 
its drum-like pedicel, and thence through many forms to 
the great disc and pedicel of Cataseta.” If the transition 
steps in the development of the appendages to which the 
pollinia attach themselves, can be thus traced from plants 
so different in this respect as Orchis and Catasetum, how 
much easier must that be from Hpidendree to Vandew ! 
The subject of the present plant is a very lovely one; its 
graceful form, and the purity and brilliancy of its white, 
and the vividness of its reds, render it one of the most 
beautiful Orchids of its type and habit, which remind one a 
good deal of some Celogynes. It was sent from the west 
coast of tropical Africa (probably Old Calabar) by Mr. W. 
Kalbreyer, who desired that it should commemorate the 
services of the late G. Thomson, a well-known resident on 
that pestilent coast. I am indebted to Mr. Veitch for the 
loan of the specimen here figured, which flowered at the 
Royal Exotic Nurseries in October, 1879. 
Descr. Pseudo-bulbs seated on a running rhizome, one 
inch in diameter, orbicular, depressed, covered with mem- 
branous scales. Leaf solitary, six to eight inches long, 
lanceolate, acuminate, membranous, plaited. Peduncles one 
or two from the base of each pseudo-bulb, ascending, slender, 
pubescent, with one or two spathes, two-flowered; bract 
sheathing, subacute. Flower three to three and a half inches 
across the petals; perianth widely spreading. Sepals and 
petals pure white; dorsal sepal erect, oblong-lanceolate, 
acuminate, margins reflexed below the middle ; lateral sepals 
smaller and narrower. Petals horizontal, lanceolate, acumi- 
nate. Lip trifid, side-lobes erect, conchoid, subquadrate, 
streaked with red inside; mid-lobe elongate-triangular, one 
inch long, gradually tapering to a recurved point, white 
with broad red streaks. Column arched, semi-terete, green 
streaked withred. Anther deflexed, ovate-lanceolate, obtuse. 
Pollinia eight in two bundles, small, pyriform, their caudicles 
united into one thick one seated on asmall gland.—J. D. H. 
Fig. 1, flower with sepals and petals removed; 2, column and lip; 3, anther; 
4, pollinia :—-all enlarged. 
