13 



THE DIVISIONS OF EXOGENS. 



Table IL 



THE B &LANOPHORAL, OR EPIGYNOUS DIVISION. 



That the Epigynous Exogens, or as I have termed them the Balanophoral Division, are really related to the Bryacece, may I believe be assumed, because the involucre (perianth) of 

 Jungermanniacem may be regarded as analogous to the involucre so remarkable in the Epigynous families, especially in Cham&lauciacece, Calyceracece, and Dipsacece the dense inflorescence of 

 some Bryacece (50 archegonia on one stem) may be a near approach to the densely crowded spikes of Balanophoracece ; a further comparison is offered in the close resemblance in appearance 

 between the paraphyses of the former and the paraphysiform filaments occurring in the inflorescence of Helosidece and other sections of the latter ;— and it may also be confidently anticipated that 

 Bryacecz will agree with Balanophoracece in the physiological character of parasitism. (V. Linn. Proc. vol. V. p. 50.) It appears to me not improbable that the calyptra is a carpel, and, if so, may 

 not the theca be a polyembrynous seed, its operculum an embryotega, and its inversion a tendency to become anatropous, as in the Coniferce? And although the theca as thus understood 

 represents an ovule, yet as it has internally the structure of an anther as far as regards the production of spores (like the ovules of Passiflora when producing pollen, Trans. Linn. Soc. 

 Vol. XXIV., p. 143), the occurrence of a columella in the anther of Mysodendron punctulatum (Flor. Antarct. Vol. IL, pi. 104, fig. 5 & 6), may be a very singular coincidence in structure between 

 Loranthacece and Bryacece (v. p. 7,) and offer an unexpected explanation of the origin and nature of the columella, in the latter hitherto obscure or unknown. The seta may be analogous to 

 the jointed filament of Melastomacece, the articulation in the former being generally at its base but not always (Sphagnum), instead of towards the apex ; and the peristome to a tuft of scales on 

 the apex of the half-superior ovary of Centradenia. 



As far as my observation has extended, the line of separation as it may be termed, between the Epigynous and the other Divisions of the Class Exogens, is quite distinct, so far as that every 

 family belongs decidedly to one or other of them. Between their apetalous and monopetalous forms there is no approach which can be regarded as showing a decided affinity, from which it may be 

 expected that the approaches between them in their polypetalous departments, although so close, are only analogies. The nearest approaches appear to be in the families Humiriacece and Saxifra- 

 gacece ; but the first may without doubt be regarded as StyracecE with a superior ovary, having no near affinity with any of the Perigynous or Hypogynous families ; and the latter have parietal placentae 

 in those genera which most nearly approach Rosacece as Tiarella, although the upper part of the ovary is deeply bifid, and indeed it still appears to me a question whether the approach between Saxi- 

 fragacece and Rosacea is more than an analogy, because, otherwise, Hydrangeacea would be very near Leguminosce.* 



I have already noticed that in the apetalous families of the Epigynous Division the raphe is always dorsal in pendulous anatropal ovules, with the exception of Garryacece where it is 

 lateral ; and it is also remarkable that in this Division the raphe next the placenta in pendulous ovules occurs only in highly developed families, and (with the exception of Umbelliferce and 

 Araliacece) only where they approach the Perigynous and Hypogynous. 



* It is difficult to suppose that Saxifragacece are in closer affinity with Rosacea than Hydrangeacece are, or even Cunoniacece and Philadelphacece, because the genus Vahlia has a I -celled ovary consisting of 2 carpels with 2 pendulous 

 placenta3 attached to the apex directly beneath the styles, the placentas being covered with small very numerous ovules, the placentation resembling that of Garrya (v. Appendix) and Hydnora. The apetalous forms of the Cornal and Rosal 

 Alliances have no affinity with each other. 



