162 MR. J. SCOTT ON THE STERILITY AND CROSS-IMPREGNATION 
tatis, breviter petiolatis, primum precipue ad venulas pilosulis, deni- 
que supra glabrescentibus, racemis przecocibus multifloris erectis 
apicem versus ramulorum confertis, bracteis minutis ovatis caducis, 
floribus pedicellatis 3—4-fasciculatis, petalis membranaceis calyce lon- 
gioribus, ovario glabro. 
Hab. Old Calabar, collected by the Rev. W. C. Thomson. 
But two species of this genus were previously known, viz. 
P. Malayana and P. Madagascariensis, natives respectively of the 
Malayan peninsula and of Madagascar. P. Guineensis forms, 
therefore, an interesting addition to the few congenerie repre- 
sentatives in West Tropical Africa of purely Malayan or of 
Malayan and at the same time Madagascar or Ceylon species. 
This new Paropsia differs remarkably in habit from its congeners 
in its precocious flowers, which are arranged in leafless racemes 
crowded towards the ends of the branches instead of in the axils 
of the leaves. The flowers, however, are fascicled in the axils of 
minute caducous bracts. Excepting in the more membranous 
and glabrous petals and glabrous ovary, I do not remark any 
important difference in the flowers of P. Guineensis, unless it bea 
tendency of the ovules to develope towards the upper part, or 
above the middle, of the placentary lines of the ovary instead of 
below the middle, or towards the base of the cavity. 
On the Individual Sterility and Cross-Impregnation of certain Spe- 
cies of Oncidium. By Mr. Joun Scorr, of the Royal Botanic 
Gardens, Edinburgh. Communicated by C. Darwin, Esq., - 
F.R.S. & L.S. 
[Read June 2, 1864.] 
THE writings of Kölreuter, Gärtner, and others furnish us with 
several illustrations of hermaphrodite plants whose two sexual 
elements are so modified in their action on each other that they 
are utterly sterile; the individual goodness of both the male and 
female elements being nevertheless shown by their facility m 
uniting with other individuals of the same species or with distinct 
species. With the view of further illustrating these singular 
phenomena, I, at the suggestion of Mr. Darwin, commenced 4 
series of experiments, in repetition of those made by previous 
observers, as well as original experiments on distinct subjects. I 
have already communicated a few of these to the Botanic Society 
of Edinburgh (vide ‘ Proceedings,’ 1863), of which, from their more 
or less immediate relation with the present notice, I will give a 
ENEE eege 
