THE ENTOMOLOGIST. 223 



every other tree ; and, with huge plants of" two other ferns 

 (Angiopteris evecta and Aspleniura nidus), forms the main 

 mass of the vegetation." And he adds, " I have nowhere 

 seen ferns in so great proportionate abundance," This 

 unusual proportion of ferns is a general feature of insular, as 

 compared with continental, floras; but it has, I believe, been 

 generally attributed to favourable conditions, especially to 

 equable climate and perennial moisture. In this respect, 

 however, Tahiti can hardly differ greatly from many other 

 islands, which yet have no such vast preponderance of ferns. 

 This is a question that cannot bfe decided by mere lists of 

 species, since it is probable that in Tahiti they are less 

 numerous than in some other islands where they form a far 

 less conspicuous feature in the vegetation. The island most 

 comparable with Tahiti in that respect is Juan Fernandez. 

 Mr. Moseley writes to me : — " In a general view of any wide 

 stretch of the densely-clothed mountainous surface of the 

 island, the ferns — both tree-ferns and the unstemmed forms — 

 are seen at once to compose a very large proportion of the 

 mass of foliage." As to the insects of Juan Fernandez, 

 Mr. Edwyn C. Reed, who made two visits, and spent several 

 weeks there, has kindly furnished me with some exact 

 information. Of butterflies there is only one (Pyrameis carie), 

 and that rare — a Chilian species, and probably an accidental 

 straggler. Four species of moths of moderate size were 

 observed — all Chilian, and a iew larvae and pupae. Of bees 

 there were none, except one very minute species (allied to 

 Chilicola); and of other Hymenoptera, a single specimen of 

 Ophion luteus — a cosmopolitan Ichneumon. About twenty 

 species of flies were observed, and these formed the most 

 prominent feature of the Entomology of the island. 



Now, as far as we know, this extreme entomological 

 poverty agrees closely with that of Tahiti ; and there are, 

 probably, no other portions of the globe equally favoured in 

 soil and climate, and with an equally luxuriant vegetation, 

 where insect-life is so scantily developed. It is curious, 

 therefore, to find that these two islands also agree in the 

 wonderful predominance of ferns over the flowering plants — in 

 individuals even more than in species ; and there is no 

 difiiculiy in connecting the two facts. The excessive 

 minuteness and great abundance of fern-spores cause them 



