22 ON GENERA AND SPECIES. 



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

 became by purchase the owner of the Linnean Herbarium. 

 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. : Darea, Scolopendrium, Woudwardia, 

 Lindscea (Dryander, MS.), Vittaria, Davallia, Dicksonia 

 (L'Heritier, 1788), Cyathea, Hymenopliyllum, Schizcea, 

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

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

 under two sections viz., Annulatce and Exannulatce. The 

 technical difference between these consists in the spore 

 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 organ which 

 I have already described under the name of indusium, by 

 some called involucrum. Although this organ was noticed 

 by Adanson and Necker, yet it was not employed by 

 Linnaeus 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 Both, and was adopted by Swartz in the above- 

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

 * Afterwards Sir James Edward Smith. 



