ILLUSTRATIONS OF INDIAN BOTANY- 



175 



of these genera are either unnecessary or inadequately defined. Between Ophelia and Swertia, 

 forexaraple, if really distinct, the distinguishing characters do not seem well brought out, neither 

 do those between Canscora and Pladera seem quite satisfactory, while, judging of Cicendia 

 from C. fastigiata, I can discover no difference between it and Pladera. It is true that none 

 of these genera are his and to that extent he is not accountable for them, but it does appear to 

 me that, when revising a whole order, and reconstructing the characters of its genera, tlie author 

 is not bound to preserve genera originally based on imperfect observation and perhaps bad 

 materials, or on insufficient examination. The genus Ophelia^ as it now stands in DCs. Prod, 

 is a very difficult one. This, I believe, is in some measure owing to Griesbach having 

 unfortunately selected, as the basis of his divisions, the form of the filiments which, accord- 

 ing to my experience, do not supply good sectional characters, being with a few exceptions 

 all too much alike. The form of the pores and their appendages seem better adapted for 

 the purpose, as being more easily appreciable and more constant. In some, for example, the 

 pore is completely covered with a scale larger than itself, and nearly entire or slightly 

 fimbriated on the margin ; in others the scale is smaller and fimbriated on the margin with 

 long bristles or lacinese; and in others again it is attached to the upper half of the pore, 

 entire on the margin, and pendulous like a curtain ; and lastly a few have no proper pore, 

 its place being supplied by a glandular thickening. Availing ourselves of such marks as 

 these, the genus might be divided as follows : 



Pore covered by a scale, free on the margin. 

 Scale attached to the lower edge of the pore, ascending. (Figs. b. c.) 

 Scale attached from above, entire on the margin, pendulous, (d. e.) 

 Pore not covered with a scale but bound by a raised margin. 



Margin broad, sub-saccate, beset on the edge with long, coarse bristles, concealing the pore, (f.) 

 Margin narrow, bristles short, inflexed over the pore, (g.) 

 Pore wanting, its place supplied by a naked, glandular disk, or by minute, inconspicuous dots, (h.) 



This example will, I trust, suffice to show the use that might be made of that organ 

 m distributing into sections the species of this very difficult genus. The author of the mono- 

 graph does not seem to have observed this point of structure with adequate care as it strikes 

 me I more than once, when studying the genus, stumbled on cases where the pores were incor- 

 rectly described, conveying the impression that he thought them of but small value in furnish- 

 ing specific characters. 



Before quitting Ophelia^ I would direct attention to the section of the ovary as exhibiting 

 an example of 4 placentae and, according to the view I take of that structure, indicating a 

 like number of carpels. It is with reference to this peculiarity that I made the addition, within 

 brackets, appended to the character of the order. 



EXPLANATION OF PLATE 157. 



Haltnia Perroitetii (Griseb.) nat. size. 



1. Unopened flower. 



2. Flower full-blown. 



3. Detached corolla split open, stamens in situ 



4. Anthers, back and front views. 



5. Calyx and ovary. 



6. Ovary detached and magnified. 



7. Ovary cut transversely. 



8. The same enlarged and forcibly dilated to separate 

 the approximated, but not adhering, inflexed margins of 

 the carpels, forming, in this genus, a spurious partition. 



9. Ovary cut lengthwise. 

 Mature capsule, a little enlarged* 

 Seed much magnified. 

 Cut vertically, embryo in situ. 



10. 

 11. 

 J2. 



13. Detached embryo. 



EXPLANATION OF PLATE 157-b. 



'• Exacum Walkeri, Amott — 5. transverse section of an 



TT*'* ^'Shly magnified — the other numbers as usuaL 

 11. A. Canscora alata, fig. 6. section of the stem show- 



Ill. 



mg the wings. 

 B. Cicendia fastigiata, or Pladera pusiUa. 

 a. Ophelia umbellata {R.W, Herb.l 



D. OpheUa affinis (W. & A. MSS.> 



d. 



e. 



f. 



Bb.l 



I 



(W. & A. MSS. . 



(W. & A. MSS.). 



g. upn. iricuoiuijua 



L Oph. cordata (Don). 

 IV. Limnanthemum cristatum. 



