however, for thèse reasons propose the union of Cyrtochilum and Oncidium, which I think may be
distinguished satisfactorily in the following manner. ' Oncidium always has the two lateral sepals
either more or less united or distinctly approximated at the base, Cyrtochilum has them equally
spreading ; on this account my C. Karwinskii must be reduced to Oncidium, notwithstanding its
entire lip, with lamellae in lieu of tubercles at its concave base. In the second place, the lip of all
true Çyrtochila is narrowed towards the apex, while in Oncidium, except in those species where it
is deeply hastate, it is dilated and rounded at the apex.
With respect to Odontoglossum, it was first distinguished by an unguiculate labellum adnate
half-way up the face of the column, a reflexed lamina with three subulate tubercles at the base, and
a column with two auricles. Of these characters the first is not found in any species I have
examined, and probably arose in some mistake ; the others are inconstant. Thus the reflexed
lamina, although characteristic of some species is not of others; in Odontoglossum nebulosumm,
lacerum's), Hallii, cirrhosum, &c. it is a conspicuous feature, but it can hardly be observed in
O. Rossii<#), and maculatum (or cordatum of the Botanical Register), and it does not exist at all
in O. Cervantes», which is very near O. nebulosum. The nature of the tubercles is also I suspect
misunderstood in the species to which it is assigned ; for while two teeth or setae are common, I do
not find the number three in any case except 0 . lacerum, and then it is accompanied by other
characters. The presence or absence of auricles upon the column is not to be taken as a generic,
character, because it has already been shewn that the character is inconstant in Oncidium ; because
it is equally variable in Cyrtochilium, of which C. volubile is really a species ; and because they are
absent in Odontoglossum pardinum (Cyrtochilum pardinum, Gen. et Sp. 210), nebulosum, Cervantesii
and Rossii, while they are present in O. membranaceum(10), which is hardly distinguishable from
the last, and in several other species.
The true characters of Odontoglossum, and those by which alone it can be distinguished gene-
rically from Cyrtochilum and Oncidium, are a long column, and an entire unguiculate lip, narrowing
to the point, and furnished at the base with a pair of fleshy, entire, or fringed lamellæ, in front of
which stand two, or rarely three, teeth or bristles. In this view of the question, Mr. Bateman’s
Cyrtochilum bictoniense will belong to Odontoglossum ; while my own Cyrtochilum ixioides, which
I once thought would best arrange with Odontoglossum, will retain its original position.
In conclusion, the differential characters of Oncidium, Cyrtochilum, Miltonia, and Odonto- j
glossum, may now be considered settled as follows ;
O n c id iu m . Sepala lateralia labello supposita, nunc connata. Labellum datum, panduratum v. trilobum, apice dilatatum, basi sæpiùs varié tubpelarcnuulmat,u smæ.piùs sessile, corC
y r t o c h il u m . Sepala lateralia patula, libera. Labellum planum, oblongum, sæpiùs unguiculatum, integrum vel margine dentatum, apice angustatum, basi tuberculatum villosum aut pluriès làmel- latum.
M il t o n ia . Sepala lateralia patula, libera. Labellum sessile, integrum, explanatum v. cucullatum,
apice rotundatum, venis baseos pluriès tuberculato-lamellatis.
O d o n t o g l o s s u m . Sepala lateralia patula, libera. Labellum planum, unguiculatum, ascendens, limbo reflexo diviso dentato, apice angustato ; basi concavum cristâ bilamellatâ rarô fimbriatâ sepiùs anticè bidentatâ auctum. Columna elongata, apice auriculata aut aptera.
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