14 On a neiv Arrangement of Phanerogamous Plants. 



(PI. III. fig. 10) it may be expected that this genus is another 

 instance among Aracete in which the placentation is dorsal, as 

 the fissure of the stigma is in two instances represented as 

 taking place toward the axis (Trans. Linn. Soc. vol. xx. tab. 10). 

 Fissures occurring in the stigmas of single carpels are generally, 

 if not without exception, dorsal, and in Sparganium ramosum such 

 fissured stigmas are not unfrequent, the fissure being always 

 dorsal (PI. III. fig. 9), which is so far a reason for regarding the 

 5-7-celled ovary of Cryptocoryne as produced by the carpels of 

 as many separate flowers. As thus luiderstood all the carpels 

 are posterior having their placentation dorsal, and become ad- 

 herent, so as to form in appearance one polycarpous ovary ; and 

 although this may appear problematical, it would be difficult to 

 account for the structure of Cryptocoryne on the ordinary rules 

 of carpology, as Mr. Griffith alludes to other species in which 

 the carpels are more numerous, and adds that he should not be 

 surprised if species be found to exist with ovaria disposed in two 

 or more series, which then would nearly appi'oach Arum. 



The ovaries of difierent flowers becoming confluent so as to 

 form a syncarpous mass is not without parallel, as in the mon- 

 strous ovaries of Matthiola incana it is a very common irregu- 

 larity that two ovaries, and also three standing in a row, form 

 only one cavity ; the confluence taking place at the dorsal suture, 

 or so near it as to be in each case intermediate between the two 

 placentre, from which it seems possible that this may take place 

 as a regular structure. And in Opercularia also adhesions take 

 place between the capsules constituting the small whorls of fruits 

 which remain permanent after complete dehiscence has taken 

 place. 



While however dorsal placentation forms an important devia- 

 tion in the ^-ucture of ovaries, its value as a character in sepa- 

 rating near allies is but weak, Monodora among Anonacese being 

 a remarkable example of ovules deriving their attachment from 

 the whole of the inner surface of an ovary consisting of a single 

 carpel, and that in an Alliance which has otherwise ordinary 

 modes of placentation. But, on the contrary, those families 

 in which it occms may on that account prove to have a direct 

 affinity to each other ; and it most probably is, in common with 

 the posterior position of the carpel, and the raphe averse in pen- 

 dulous anatropal ovules, an Endogenous character, and shows an 

 approach (where it occurs) on the part of Exogens to Endogens. 



EXPLANATION OF PLATE IIL 



Fig. \. The external appearance of a carpel of Nelumbium speciosum, show- 

 ing the ventral tuberosity which is always turned towards the 

 stamens. 



Fig. 2. The same as seen laterally. 



Fig. .S. A longitudinal section of it : a, the ventral tuberosity. The funi- 



