22 ON GENERA AND SPECIES. 



J. E. Smith,* who, after the death of the younger LinntBus, 

 became by purchase the owner of the Linnean Herbarinm. 

 He published many botanical memoirs, and one on Ferns 

 in 1793, in the fifth volume of the "Memoirs of the 

 Academia of Turin," in which he characterised thirteen 

 new genera — viz. : Varea, Scolopendriiim, Woudwardta, 

 Lindsma (Dryander, MS.), Vittaria, Bavcdlia, Dicksoivia 

 (L'Heritier, 1788), Cyathea, Hymenophylluiii, ScJiizcea, 

 Gleichenia, Maraitia, and Dancea. These, with the Linnean 

 genera, raised the number to twenty-four, which he divides 

 under two sections — viz., Annulatce and Exannulalce. The 

 technical difference between these consists in the sjjore 

 cases being furnished with a ring, or destitute of a ring. 

 This mode of arrangement has since been adopted by all 

 systematic writers on Ferns, as defining- two distinct orders 

 which will come under special notice hereafter. 



The next general systematic work was the " Synopsis 

 Filicum" of Dr. Swartz, published in 1806. In that ex- 

 cellent work nearly 700 species are described, and a 

 great many doubtful species enumerated. The de- 

 scribed species are classified under thirty-six genera, being 

 an increase of twenty-five since those of Linnaeus. Eleven 

 of them are founded on species removed from Linnean 

 genera, their separation being due to a special oi-gan which 

 I have already described under the name of induslum, by 

 some called involucrum. Although this organ was noticed 

 by Adauson and Keeker, yet it was not employed by 

 Linnasus in characterising his genera. It was first specially 

 made use of by Sir J. E. Smith, in characterising his new 

 genera, and also about the same time by the German 

 botanist Roth, and was adopted by Swartz in the above- 

 named work, in which he arranges twenty-five of the 

 * Afterwards Sir .Tames Edward Smith. 



