they are "compared to the corresponding mathematical forms." This would make oblong' a parallelogram; but all that seems to be implied in the term is that the two long sides of the leaf are parallel to some extent in the proportion of length and breadth there is but little agreement among authorities. 'Oval' and 'elliptical' are doubtless synonymous in geometry, and Linnæus (Phil. Bot.) employed them in the strict mathematical sense; they are still used interchangeably by many botanists to indicate a figure about twice as long as broad, broadest in the middle, and equal at the ends, which may be either rounded or pointed. In Professor Oliver's outline figures, however, elliptical' is a figure broader than 'oval' in the proportion of 3 to 2. Other descriptive botanists distinguish between oval' with the apex and base graduated to a point, and elliptic' with the ends rounded, and the sides more or less parallel. It appears to me that a combination of or compromise between the views of different writers might be effected with advantage, and the four terms made to cover all the forms of simply-outlined leaves equal at both ends in the following manner, in no case giving a new signification to a term, though the proposed definition of oval is not that which it originally possessed :-
Leaf tapering from the middle equally to base and apex- About twice as long as broad =oval. About thrice " = lanceolate. Leaf with more or less parallel sides and blunt extremities- About twice as long as broad=elliptic. About thrice" = oblong.
Intermediate forms can be expressed by combination of these terms, and forms where either the base or apex is the broader by the use of ovate or obovate, alone, or in combination with one of the terms above defined. Whatever definitions be adopted, at all events it is very desirable that greater uniformity should be secured than at present exists.-HENRY TRIMEN.
MIDDLESEX PLANTS.-On some waste ground near the new South West India Docks I noticed last month (October) a very large quantity of Aster Tripolium, both rayed and not rayed. On the same ground occurred as introductions Senecio viscosus and Xanthium spinosum. The latter is not given as a Middlesex plant in the published Flora of that county. I may also mention that in 1866 I collected Xanthium Strumarium at Chelsea; the latest date in the Flora is 1746, and the plant is bracketed as "probably extinct." I have shown my specimens to Dr. Trimen. F. NAYLOR.
NOTE ON THE SUPPOSED CERASTIUM PUMILUM FROM JERSEY (sce ante, p. 199).-As Dr. Trimen has been kind enough to allow me to see some more specimens of the Cerastium which he gathered on the sand- hills of Jersey, I think it may be as well to state here that, on a second examination, I have found no reason to change my former opinion, and I believe the plant is typical C. tetrandrum, not C. pumilum. So far as my 2 B 2
