23 



Table IV. 



The Ceratophyllinal or Dorsal Placentation Division. 



That the families here brought together are all very naturally conterminous with each other will probably not be doubted (with the exception of Gentianacece), but whether taken as a whole, 

 they constitute a distinct Division of the Exogens, or are a retrograde branch of the Platano-Proteal Division, Table VI., may perhaps admit of further arguments ; — to combine them, however, 

 with Table VI. or with Table V., to which they are also closely allied, would bring together a mass of families much too large to form one Division. 



The most remarkable character in this Division is, that the placentation is in a part of the families, dorsal, viz. in Ceratophyllacece, Hydropeltidece, Nymphceacece, Gentianacece, 

 Lardizabalece, Anonacece, and Combretacece ; and in it are probably included all the exogenous families where the placentation is really dorsal, as in Mesembryanthemum Payer has shown that the 

 branches of the placenta are displaced and adhere to the dorsal ribs of the ovary, and this may be the case in Orobanchacece, v. Appendix. This being admitted, these families so far may be regarded 

 as having a peculiar relation to each other, and it may be deserving of notice, that the five exogenous families having ruminated albumen, Myristicacece, Anonacece, Menispermacece, Ebenacece, and 

 Dipterocarpea, also have their natural stations in this Division. And I would further suggest, that the contortuplicated condition of the cotyledons of Dryobalanops, Dipterocarpus, and Doona, 

 may be analogous to ruminated albumen, especially if the testa is induplicate, and if so it would assist in proving the true station of Ancistrocladus to be with Dipterocarpece. From the descriptions 

 of the seeds of these genera, the contortuplicated character of the cotyledons would appear to be almost, if not quite, identical in the mode of its formation with that of the ruminated albumen of 

 the common nutmeg. The albumen of the nutmeg consists of 8 or 10 rather irregular longitudinal plates extending from the base to the apex of the seed, which are again repeatedly subdivided 

 near the surface, and it is these smaller fissures which give the transverse section a perforated appearance. The plates form one continuous mass in the centre in the same way as the convolutions 

 of the embryo of the walnut all unite in the cauliculus, so that no portion of it can be separated without a fracture. Its testa consists of two coats, or at least of two quite distinct layers, which are 

 readily separable, and of these the external completely envelopes the albumen, sending down no processes between its plates, but the internal does so, and the infolded portions extend almost to 

 the base of the laminae of the albumen, i.e., nearly to the centre of the seed, although they do not extend into the smaller fissures. This suggests that contortuplicated, cerebriform, or laminated, 

 would be a better term for such an albumen than ruminated, which probably refers to the specks seen in a transverse section, but these are only the terminations of the more superficial fissures. 



If the attachment of the spore cases in the globular involucre of Pilularia can be compared to dorsal placentation, which may be admissable, because it shows an unusual tendency to growth 

 from the mid-rib, there may prove to be a very close approach between it and Ceratophyllum, and on this account I have placed Marsileacece as the cryptogamous form of this Division.* An 

 analogy may also exist between Marsileacece and a part of the families here included, in the circinate vernation of the leaves, as in Nepenthacece and Droseracece. Ophioglossum peduncidatum and 

 Pyrola uniflora die when they flower, and are reproduced by root-buds of adventitious roots (Currey's Transl. Hofm. p. 315), which perhaps may lend some support to the opinion that Ophioglos- 

 sacece are the basis of this Division. 



In Ceratophyllum the carpel is always posterior/}* from which it would appear that it is a retrograde form of some genus or a family, perhaps now extinct, in which the carpel is always 

 anterior — ; in the position of the carpel it is an exception as regards the primitive forms of the Divisions. 



The Erical and Ternstroemial Subdivisions may not be sufficiently distinct, M. Planchon having pointed out an approach of Ternstrcemiacece to Ericacece. 



* May there not be a connection between the compound anthers of Lauracece (the anther with four or six valves) and the compound male inflorescence of Marsileacece? In monstrous flowers of Matihiola incana I have met with ovaries in 

 which the carpels were not united, and had become antheriferous on their margins (or one margin was antheriferous and the other bore ovules), but instead of bearing one anther lobe the polleniferous mass was divided into several distinct 

 portions of various sizes. Is not this in some degree analogous to the male inflorescence of Salvinia f 



f Those families in which the carpel is always posterior are, I believe, always retrograde forms of others in which it is always anterior. 



