J. SMITH ON THE GENERA OF FERNS. 195 



93. PoLYSTiCHUM, Rolh., Presl., J. Sm, 



(Aspidii sp. Sw. and Aiitk. Hypopeltidis sp. Mich. Tec- 

 taria, Cav. Rumohra, Radd,) 



Veins pinnately-forked ; venules direct, free, the lower ex- 

 terior one or more fertile ; sporangia medial, rarely terminal ; 

 sort round; indusium orbicular, central, rarely eccentric and 

 reniform. 



Fronds simple, pinnate, or hi-tripinnate ; pinna; u&uullif 

 auriculated at the base on the superior side, the margin usu- 

 ally serrate, the sen^atures or dents terminating in a rigid 

 mucrone or spinule. 



Species. 1. P. glandulosum, (^ffook. et Grev.) 2. P. rhizo- 

 phyllum, (Sw.) 3. P. trapezoides, {Sw.) 4. P. falcinel- 

 lum, [Sw.) 3. P. caespitosum, ( Wall.) 6. P. Lonchitis, 

 Roth. 7. P. acrostichoides, (Sw.) 8. P. munitum, {Kaulf.) 

 9. P. lobatuni, (Sw.) 10. P. angulare, iCitoi. 11. P. ves- 

 titum, {Sw.y 12. P. proliferum, i2. Br. 13. P. aculeatum, 

 Roth. {Sw.) 14. P. platyphyllum, {WiUd.) 15. P. coria- 

 ceum, {Sw.) Tectaria, Car., Link. Rumohra, Radd.) 16. 

 P. aristatum, {Sw.) 17. P. hispidum, {Sw.) 18. P. speeio- 

 sum, (Don.) 19. P. denticulatum, {Sw.) 20. P. conii- 

 foiium, ( Wall.) 



Rlust. Schott. Gen. Fil. t. 9. Hook. Gen. Fit. t. 48. C. 



Obs. This is also an extensive genus, and distinguished 

 from Lastrea by its rigid and spinous habit; for, although the 

 generality of the species have a truly orbicular indusium, yet 

 there are many species, but especially those with decompound 

 fronds, which have the attachment of the indusium eccentric, 

 or even lateral; however, the dry rigid habit of these species 

 clearly shows that they belong to the same group which have 

 centrally attached indusia. The indusium in several species 

 of this genus is remarkable in becoming bypocratiform, which 

 takes place by the pressure of the sporangia underneath, rais- 

 ing the free circular margin of the indusium. 



