P L Y P D I A C E M. 189 



venules only anastomosing, and the sori, moreover, are seated at a 

 greater distance from the costseform vein. 



Plate 25. — Fig. 1. Portions of a frond, of the natural size. 1 a. 

 Section of a pinna, showing the position of the sori, and the tubercles 

 on the under surface. 1 b. Sorus. 1 c. Indusium. 1 d, d. Sporangia. 

 1 e. Sporules. — Magnified. 



7. Nephrodium unitum, B. Br. ? 



Nephrodium unitum, R. Br. Prodr. Fl. Nov. Holl. p. 148 ? Hook. Gen. Fil. t. 48, 



B, f. 6. 

 Aspidium unitum, Hook. & Arn. Bot. Beech. Voy. p. 256. 



Hab. Tahiti, Society Islands. Feejee Islands. 



There are two states of this in the collection : one with large and 

 somewhat lax fronds, and linear-attenuated pinnae, the inferior ones 

 considerably the smaller : the other form with erect and rather rigid 

 fronds, and shorter ensiform pinnae. In both varieties the fronds are 

 smooth on the upper surface, and with two or three of the opposite 

 pairs of venules anastomosing. In this particular, as also in the fronds 

 being pubescent beneath, it agrees with the plant of Hooker and 

 Arnott, as represented in Hooker's Genera Filicum, where the sori 

 are shown as being produced only on the free venules ; while in our 

 plant they are borne on the anastomosing venules alike with the free, 

 and are furnished with a slightly hairy indusium. We are not alto- 

 gether satisfied that this is truly the N. unitum. of R. Brown; but 

 have no doubt of its being the plant of Hooker and Arnott. 



8. Nephrodium cyatheoides, J. Sm. 



Nephrodium cyatheoides, J. Sin. in Hook. Jour. Bot. 4, p. 188. 

 N. Dubrueilianum, Hook. & Arn. Bot. Beech. Voy. p. 105. 

 Aspidium cyatheoides, Kaulf. Enum. Fil. p. 234. 

 Polystichum Dubrueilianum, Gaud. Bot. Freyc. Voy. p. 333, t. 9. 



Hab. Sandwich Islands : along the banks of streams, frequent. 



48 



