482 SYSTEMATIC BOTANY. 



the Convolvulacese and the Boraginaceae, as a distinct family, principally in 

 consequence of the absence of the style, and the one-celled ovary. 



HYDKOLEACE.E. They have been worked out in the Prodromus (vol. x) 

 by Choisy. A. De Candolle remarks that in Hydrolea the dehiscence of the 

 capsule is margiuicidal, whilst in the other genera it is loculicidal ; and he 

 thinks that in the latter the ovary ought to be regarded as unilocular with 

 placentae projecting toward the axis, whence he prefers uniting them with 

 the Hydrophyllacese. Choisy takes the opposite view, without, however, 

 enfeebling this argument. 



HYDROPHYLLACE.E. They are treated of by A. De Candolle in the Pro- 

 dromus (vol. ix), who separates Eutoca into two types Microgenetes from 

 Chili, and Miltitzia from California. 



POLEMONIACE^E. Also described by Bentharn in the above work. 



CONVOLVULACEJE. Choisy's description in the Prodromus (ibid.) is in- 

 ferior to the other parts of the work in a critical point of view. The new 

 genera admitted are Marcellia Mart, from Brazil, and Seddera Hochst., 

 Steud., from Abyssinia. Pfeiffer (Bot. Zeit. 1845, p. 673) separates Owcuta 

 epilinum from the genus Cuscuta as Epilinella, as this species possesses a 

 pentasepalous calyx ; also those species which are furnished with capitate 

 stigmata, as Engelmannia, a name which will be at once given up. 



BORAGINACE^E. A. De Candolle has described them excellently well in 

 the Prodromus (vol. ix, x), from the preparatory writings of his father, 

 and divides them into four tribes : Cordieae, Ehretieae, Heliotropeae, 

 and Boraginese. New types : Gynaion (a monstrosity of Cordia ?), from 

 the Himalaya ; Meratia, allied to Myosotis, from Caracas. Heliophytnm and 

 Pentacarya are separated from Heliotropium ; Maharanga, with a basilar 

 corona, from the Himalaya, from Onosmodinm ; Pentalophiis, from Litho- 

 spermum, from the prairies ; Qruvelia, from Chili, from Cynoglosmm ; from 

 Echinospermum, Heterocarittm, several species from the steppes of Asia. 

 Moris separates Buglossites = B. laxiflora, D. C. from Borago (Turin Cat. 

 of Seeds, f. 1845). 



AVICENNE^:. Griffith read before the Linnaean Society the history of the 

 development of the ovum of Avicennia (Proceedings of Linn. Soc., Nov. 

 1844, in the Ann. of Nat. Hist., xv, p. 197). Avicennia has a free central 

 placenta, with suspended ovules, which do not appear to possess any integu- 

 ments, and were considered by St. Hilaire as funiculi. The embryo of the 

 fertile ovule, after impregnation, grows in the axis of the nucleus on both 

 sides, passes out from its anterior surface, and there attains its principal 

 development, and which does not appear to be accompanied by the deposition 

 of albumen until it reaches the exterior of the original ovule. At a sub- 

 sequent period, a furrow is formed upon the anterior surface of the albumen, 

 and which corresponds to the points of the cotyledons of the embryo, whilst 

 the embryo-sac passes back into the placenta, and ramifies within it. Finally 



