J.SMITH ON THE GENERA OF FERNS. 69 



plan tag! neu m ; Kaulf. 6. A. reticulatum ; Kaulf. — Illust. 

 Hook, et Grev. Ic. Fit. t. 46, 74.. Schk. crypt, t. 6. 



Obs. Although I have characterized the former genus 

 Polyt(P7iium, as being distinct from Antrophyum, yet it must 

 be admitted that its technical character of having three trans- 

 verse parallel sori, depends in a great measure on the narrow 

 linear character of the frond, a nearly similar character being 

 observed in A. coriaceum, which has irregular, interrupted, 

 transverse sori, and which evidently forms a transition be- 

 tween PolytcBTiium and the wide-fronded species of Antro- 

 phyum. In some of the species, the sori are formed only on 

 the oblique sides of the areoles, thus presenting sori nearly 

 similar to Loxogramma, but that genus differs from the pre- 

 sent one by the sori being formed on the crossings or con- 

 fluence of the venules. 



36. Hemionitis. Linn, 



Venation uniform, reticulated, sides of the areoles sporan- 

 giferous. Sporangia superficial, forming complete reticulated 

 linear son. — Fronds simple, cordate, palmate or pinnate, smooth 

 or villose, areoles nearly equal-sided. Sori becoming confluent. 



Examp. 1. H. cordata; Roxb. 2. H. palmata; Linn. 3. 

 H. pinnata; J. Sm. — Illust. Hook, et Grev. Ic. Fil. t. 64. Schott. 

 gen.^l. t. 13. 



Obs. The habit of this genus is very different from the 

 former, yet I must confess that the character of superficial 

 sori is but slight grounds for separating them upon, especi- 

 ally as in A. lanceolatum, the sori are not, or scarcely, im- 

 mersed, but however slight their technical distinctions are, 

 yet I cannot allow myself to think that they should be retain- 

 ed in the same genus. 



37. Ceratopteris. Byvng. 



Fertile fronds contracted; margin (of segments) reflexed, 

 membraneous, conniving, indusiiform. Veins transversely 

 elongated, distantly anastomosing. Sporangia occupying the 

 lengthened, transverse venules, superficial, forming two linear- 



