DUBLnr NATUKAL HI8T0BT SOCIETT. 177 



they were but the one species. I do not immediately understand the 

 meaning of the point, that Ceratoptcris from the tropics was placed in 

 a separate family from Parkeria from Demerara ; but that intermediate 

 forms had been since found, which united those two different-looking 

 varieties into not only the same genus, but into the same species. Tho 

 great division of importance of ferns into groups is characterized by tho 

 Sporangia being destitute of, or furnished with, an elastic ring, thus 

 forming three sections — the exannulate, the transverse annulate group, 

 and the group with a vertical ring. 



From what I could glean from Professor Harvey's statement, he made it 

 appear that the large globose sporangia of Ceratoptcris had a broad trans- 

 verse ring ; in Parkeria it was nearly obsolete, or exannulate, which led 

 Sir William Hooker, from two specimens of one species, to form separate 

 genera ; but recent specimens, and those subsequently cultivated, proved 

 that they both possessed an elastic, not a transverse, but a vertical ring, 

 thus placing them in the one proper group. It was no error of judgment 

 of Sir William Hooker, but misconception from the examination of im- 

 perfect specimens, especially in a fern like Ceratoptcris, which presents 

 two forms of frond. The marshes of Java afford this fern in abundance. 

 The perplexity arose in the describing of plants which have not been 

 gathered in their developed or perfect state, and in the difficulty of col- 

 lectors in tropical countries preserving their herbaria, often saturated by 

 rain, attacked by insects, or injured by accidents which cannot be guarded 

 against: often have subscribers, in opening their packages, been hor- 

 rified at finding their choicest specimens unfit for examination. The 

 indefatigable George Gardner, when in the interior of Brazil, in the pro- 

 vince of Goyaz, laments the sad misfortune to his dried plants. On 

 crossing the Rio de Peize his horse stumbled, and the packages of the 

 entire of his labour for weeks in a district hitherto imexplored by bo- 

 tanists, were immersed, and completely saturated. Even Mr. Bentham 

 admits these difficulties. The action of water on aquatic plants in de- 

 stroying their characters is not uncommon. In foreign herbaria, in the 

 cover of Myriophyllum, are often found specimens of Ranunculus, Ca- 

 bomba, Ceratophyllum, LimnophUa, Dysophylla, Ajiacharis, &c. The Zm- 

 nophila gratioloidea has already been described among Caryophylleae and 

 among Primulaceae. 



Again, I do not understand the observations, " that in the common 

 Hart's-tongue, fructification assumed different positions." The charac- 

 teristics of the genus are, that the sori are parallel in two rows, very 

 numerous, arranged in a longitudinal linear fissure on the frond, assum- 

 ing different lengths, and the indusium attached along both sides. Any 

 alteration of such characters must constitute a different genus. The cha- 

 racter and position of the sori establish generic distinction; the habit of 

 the plant in the same genus determines specific difference. In Teeniopsis 

 and Vittaria, which have been separated into different genera, the habits 

 of the plants of each scarcely indicate any distinction; yet in Vittaria the 

 margin of the frond is slit longitudinally, forming two narrow laminae, 



