478 SYSTEMATIC BOTANY. 



HYPEEICACE^:. Cossoii and Germain (Flore de Paris) admit Spach's 

 genus Elodea (Hypericum elodes), which differs from Hypericum in its parietal 

 placentation, whilst the latter has a central placenta. To me, however, the 

 difference appears merely to consist in the parietal placentae of Hypericum 

 meeting in the axis of the fruit, whilst in Elodea this is not the case : whether 

 this is a generic character or not must be decided by a future monograph of 

 the family, Spach's work not being sufficient for this purpose. 



CARYOPHYLLACE.E. J. Gay's monograph of Holosteum (Ann. Sc. Nat. iii, 

 4, p. 23-44) is characterised by the author's well-known accuracy ; but is 

 impaired by the prolixity which is unfortunately so frequently combined with 

 such accuracy, particularly with endless quotations. The following new 

 genera are proposed by Gay in this memoir : Rhodalsine G. (p. 25) = 

 Arenaria procumbens V. It appears to differ from all the other Alsinese, in 

 the stamens being biserial, which is, however, a very relative character only : 

 and Greniera (p. 27) = Alsine Douglasii Fzl. and Arenaria tenella Nutt. ; 

 characterised by its seeds, which are compressed discoidally. 



CACTACE^E. We are indebted, for a scientific summary of the Cactaceae, 

 to the Prince Salm-Dyck, who possesses the largest collection in existence 

 on the Continent (about 700 forms), and is also one of those best acquainted 

 with this difficult botanical group (Cactea3 in horto Dyckensi cultse, additis 

 tribuum generumque characteribus emendatis a principe Jos. de Salm-Dyck 

 Paris, 1845, 8vo). Pfeiffera S. (p. 40), is a new genus described in this work. 



CUCURBITACEJE. Wight has written in the ' Madras Journal of Science,' 

 and Gardner in the 'Lond. Journ. of Bot.' (1845, p. 401), in favour of 

 Seriuge De Candolle's view, that the middle of the carpels is situated in the 

 axis of the fruit, and that the cells of the fruit are formed by the revolute 

 incurvation of their margins, and have endeavoured to support this para- 

 doxical theory by the course of development of the ovary. According to 

 Gardner, the external wall of the fruit is formed by the tube of the calyx 

 only, with which, in Coccinia indica, the dissepiments are merely loosely 

 in contact, without adhering to it. The course of the bundles of vascular 

 tissue also, the principal trunks of which, both in this plant and in Bryonia, 

 are situated in the axis, is in favour of Seringe's view; but the principal 

 point in the solution of this question consists in distinguishing the placentae 

 from true carpels, which has not yet been accomplished. It is still extremely 

 improbable that three leaves should grow out of the point of the axis. 

 Payer remarks (Ann. Sc. Nat., iii, 3, p. 163) that at the lower joints, where 

 three vascular bundles enter the petiole, the stem of the Cucurbitaceae is 

 not furnished with tendrils, whilst on the other hand, in the case of the 

 upper leaves, according as one or two tendrils are present, it receives two 

 vascular bundles only, or the central one alone. He thus explains the 

 oblique position of the axillary bud, which is always situated opposite the 

 central vascular bundle, and thus, where as usual a single tendril only ac- 



