326 Dr. Greville on two new species of Ferns 



In looking over a small collection of Cryptogamous plants re- 

 cently gathered in the island of Tahiti by Dr. Sibbald and sent 

 by him to Professor Balfour, I found two specimens (only two, 

 alas !) of a moss which a single glance convinced me must belong 

 to the genus Spiridens ; and the capsules being in a perfect state 

 enabled me to determine this at once in the most satisfactory 

 manner. The resemblance which it bears in general character 

 to S. Reinwardtii is so marked, that at first it seemed doubtful 

 whether it might not be a mere variety, but a more careful 

 inspection rendered the specific distinctions quite apparent. 

 The new species is a smaller and more slender plant, six to 

 nine inches long or more, the leaves scarcely more than half 

 the size, the capsules more cylindrical and the subulate termina- 

 tion of the operculum considerably longer and finer. It is under 

 the microscope, however, that the most characteristic features are 

 perceived to exist in the leaves ; the margin of which in S. Rein- 

 wardtii is distinguished by a broad fiat border closely and sharply 

 toothed ; in the new species by a very narrow thickened border 

 remotely toothed. Without entering into a minute description, 

 uncalled for in so brief a notice, the following specific characters 

 may be assigned to the two mosses : — 



S. Reinwardtii (Nees) ; foliis late marginatis, acute dentatis ; den- 

 tibus approximatis ; capsulis ovato-oblongis. 



<S. Balfouriana (nob.) ; foliis anguste marginatis, remote dentatis ; 

 capsulis ovato-cylindraceis. 



This beautiful species of one of the finest genera in the family 

 I have sincere pleasure in naming after my highly esteemed 

 friend Dr. Balfour, Professor of Botany in the University of 

 Edinburgh. 



EXPLANATION OF PLATE XVII. 



Fig. I. S. Balfouriana, nat. size. 



Fig. 2. Leaf. 



Fig. 3. Margin of the leaf of S. Reinwardtii. 



Fig. 4. Ditto of that of S. Balfouriana. 



Fig. 5. Perichsetial leaves and capsule. 



Fig. 6. Peristome. — Figs. 2-6 all magnified. 



XXXV. — Notice of two new species of Ferns belonging to the 

 genera Oleandra and Polypodium. By li. K. Greville, LL.D. 

 &c* 



[With a Plate.] 



The genus Oleandra of Cavanilles, adopted by Presl and now 

 generally received for a section of the old genus Aspidium, is one 



* Read before the Botanical Society of Edinburgh, March 9, 1818. 



