On the Affinities of Ceratophyllacea. 45 



who first characterized the order, places it next to Haloragese, in 

 which he is followed by De Candolle, who arranges it between 

 that family and Lythrariae, to which it is annexed by Arnott* 

 as a sub-order; but no affinity with either has been shown, 

 beyond a vague resemblance in habit. Bartling, and also 

 Lindley, in the first edition of the work above cited, consider 

 the affinities of the order to be wholly unknown, the latter, 

 however, suggesting the query whether it be allied to Podos- 

 temeae. In the succeeding edition, Dr. Lindley takes a new 

 and wholly unexpected view, considering the genus as a sub- 

 order, or degeneration, of Urticaceae. I can perceive no par- 

 ticular resemblance between Ceratophyllum and Urticacece, 

 except that the flowers of both are apetalous and diclinous, 

 and the achenium one-seeded. It should be remarked, how- 

 ever, that the erect seed of the Urticese proper is orthotropous, 

 as was first pointed out by Brown.t This is certainly the case 

 in Urtica, Bcehmeria, and Parietaria ; but the fact has been 

 somehow overlooked by Dr. Lindley, who expressly states, in 

 the second edition of the Introduction to the Natural System, 

 that the radicle in Urticaceae always points to the hilum ! 



Our attention is next directed to some observations con- 

 tained in the excellent and elaborate Memoire sur la Generation 

 et le Developpcment de VEmbryon dans les Vegetaux yhanero- 

 games, by Adolphe Brongniart,£ which, as they have the merit 



* " Much as these suborders (Lythrarieae and Ceratophylleae) differ 

 in appearance, we have the authority of Richard for uniting them. It 

 must be confessed, however, that their chief great resemblance is in the 

 persistent calyx, free from, but surrounding the fruit." — Arnott, I. c— 

 I have never been so fortunate as to meet with the observation of Richard 

 here alluded to. 



t Appendix to Capt. Tuckey's Expedition to Congo (1808), p. 454. 



X Read before the Academic des Sciences in ^December 1826, and 

 published the succeeding year in the 12th volume of the Annates de* 

 Sciences NatureUes. 



