46 On the Affinities <y' Ceratophyllacao. 



a bud) enveloped by the persistent membrane of the nucule. 

 The points of difference, such as the want of petals, the 

 nearly sessile anthers, and the single ovary of Cer.itophyllum, 

 are sufficiently obvious ; but they cannot be thought to weaken 

 materially such peculiar and strongly marked affiinities. The 

 lower degree of develop ement, both of the organs of vegetation 

 and fructification of Ceratophyllum, are, perhaps, chiefly attri- 

 butable to the entirely submersed habit of the genus. 



If a comparison be next instituted between Ceratophyllum 

 and the order Cabombacea: or Hydropeltideas, affinities will be 

 perceived, the existence of which have been, I believe, hitherto 

 unsuspected. This order, first indicated by Richard,* and 

 considered by De Candolle as a tribe of Podophyllea?, has 

 been referred to Nymphseaceaj both by Brownt and Lindley :| 

 it is, however, a distinct order, more closely allied to Nelum- 

 biaceae than NympliEeaceue, as will be shown in the course of 

 these remarks. It includes two genera, both peculiar to the 

 American continent, viz. Brasenia,^ the only species of which 

 (B. pcltata of Pursh) abounds in ponds and slow-flowing 

 streams from Canada to Florida; and Cabomba of Aublet, 

 which comprises two species hitherto confounded, || the one a 



* Ann. du Museum, 17, p. 230. 



t Appendix to Capt. King's Voyage to Neio Holland. 



X Op.cit. ed. 2, p. 13. 



§ Schreber, Genera Planlarum (1798), ;;. 372— Hydropeltis, Michx. 

 jl. (1S03) 1, p. 321. This genus havingbeen characterized aud described 

 by Schrebor long before the Flora of Michaux was published, I see no 

 reason for adopting the name imposed by the latter, as is done by most 

 European botanists. 



II 1 subjoin the characters and synomony of the two species. 



1. Cabomba acjuatica; foliis natantibus orbiculatis ; floribus lutcis ; 

 ovariis (an semper'!) 2. — C. aquatica, Aubl. pi. Guian. 1, p. 321, t. 

 124; Richard, ann. museum, 17, p. 230, t. 5, fig. 23; DC. syst. 2, 

 ^.36; Diet. sci. nat. t. absque num. (opt.); Roem. Sf Schult. sysl. 

 7, p. 1379 Hab. In stagnis et rivulis Cayenne, Aublet ; in Suri- 

 nam, Dr. Herring. 



