ANDREWS ON HYMENOPHYLLA. 77 



in Hooker's New Zealand Flora; but the involucres are even and 

 entire, similar to H. Wilsoni, as the specimen shows. Of H. unilaterale 

 of New Zealand, of which the specimen before you has been named and 

 described in New Zealand, the spreading frond more nearly approaches 

 H. Tunbridgense; but the fruit, with even and entire involucres, are 

 similar to those of H. Wilsoni, with the exception that the lips of the 

 involucre are broader and not ovate. 



I have been favoured with a specimen of the true JR. unilaterale 

 from Eeunion, obtained by "Dr. Keller, and named by Bory St. Yincent. 

 It unfortunately has no involucres, yet the character of the pinnules 

 of the frond are distinct both from II. Tunbridgense and JR. Wilsoni. I 

 expect a better specimen. In the meantime I will give the account of 

 one who has taken much interest in the study of ferns, especially those 

 of the Mauritius, from which place the communication is sent. I 

 should mention that Eeunion is the name given by the French to the 

 Isle of Bourbon in 1793, and resumed again in 1848. The extract, 

 which is very clear and pleasingly written, is from a letter sent to a 

 lady in this city, who is much interested in the subject : — " Hymeno- 

 phyllum unilaterale does not grow in Mauritius, but in the neighbour- 

 ing island of Bourbon (Reunion), and none has been found there since 

 1835, so that there was some difficulty in procuring a specimen. This, 

 however, has been managed with the aid of Dr. Meller, the director of 

 the Botanic Gardens here, who was in Eeunion when your letter ar- 

 rived, and who succeeded in getting me an authentic specimen, named 

 by Bory St. Vincent himself, which I now send to you, together with 

 a few of our Mauritius Hymenophyllece and Trichomanes, as they may 

 interest you or your friends. Sir Henry (Barkly)* and myself, in 

 concert with Dr. Meller, carefully examined JR. unilaterale, and we 

 came to the conclusion that it decidedly differs from the description 

 given of II. Wilsoni by Hooker in his species Filicum, vol. i., page 95, 

 inasmuch as its margin is perfectly smooth, except just at the apex of 

 the segments; while the latter is described as having the margin 

 ' toothed or spinuloso serrate,' The air cells, too, which Dr. Meller 

 examined with a microscope, are sufficiently distinct from those of JR. 

 Wilsoni in Seemann's Journal of Botany, vol. i., page 294. It also 

 appears to differ widely from the description given of H. Tunbridgense, 

 to which Sir William Hooker referred a specimen of H. unilaterale, 

 sent by Wildenow (vide species Filicum). We have not yet found IT. 

 Tunbridgense in Mauritius, and can only judge from some specimens 

 from Ireland, and from a figure given in ' Beddome's Ferns of Southern 

 India.' There can be little doubt, therefore, that R. Wilsoni is a dis- 

 dinct species — though whether the same honour can be given to II. 

 unilaterale, or whether it is only a peculiar form of some of the Bour- 

 bon varieties, remains to be proved. Sir Henry and Dr. Meller both 



* Sir Henry Barkly, K. C. B., at that time Governor and Commander-in-Chief at 

 Mauritius, now Governor and Commander-in-Chief at the Cape of Good Hope. 



