| 28 | Mr. Brown, on the Proteaceae of Jussieu. |
velope, it will be still better to call it perianthium or perigonium, which latter term was proposed by Ehrhart, and is adopted by Decandolle.
A circumstance meriting the attention of the theoretical botanist, respecting the calyx in this order, is its invariable division into four leaves or segment; for the single exception noted by Linnæus in his description of the male flowers of Brabejum, he himself seems afterwards to have distrusted, from the manner in which he has introduced it into the amended generic character given in the Mantissa; and I may add, that in nearly 400 species of the order, which I have examined, I have not met with a single exception to this rule.
With this uncommon constancy in point of number, it is remarkable that there is, in the whole order, a strong tendency to irregularity in form, the various kinds of which are of great importance in characterizing genera.
Before the expansion of the calyx the margins of its segments are applied to each other; and from the unequal degrees of cohesion in many cases subsisting among them after expansion, several kinds of irregularity arise. I am not sure that any term has been contrived for this manner of æstivation, except it be the æstivatio valvata of Linnæus; but as he has not defined it, and as his commentator Reuss has given the very different æstivation of grasses as an example, I have, in introducing this circumstance into the general description of the order, specified it at length.
From the colour of the calyx, many genera of Proteaceæ are indicated with tolerable certainty. Thus Synaphea is distinguished from Conospermum by its yellow flowers; and no instance of yellow flowers has been met with in the numerous genera Serruria and Spatalla, nor any of purple in Leucadendron. In some ge-
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