in the Lycopodiacese, Equisetacese, &c. 439 



leaf- scars are concerned. These scars are arranged in quincunx, 

 and are ovoid or elliptical-lanceolate, according to the slowness 

 or rapidity of the growth of the stem. Of the other Ferris I 

 have examined, the Oleandra presents the most marked examples 

 of the whorled structure. 



1. Cyathea (sp.). Feejee Islands. Root-stock of specimen 

 examined 45 feet long, containing 35 rows of whorls of 3 

 leaves each, placed alternately. The scars of this plant present 

 the most striking resemblance to many of those found in Lepi- 

 dodendra. The angle of divergence of the whorl is ^. 



By the suppression of alternate whorls, it would give the 

 angle |, alternate-leaved, and, by the additional suppression of 

 one-third of the remaining leaves, it would give the angle f : in 

 this latter case the reduction of leaves amounts to 67 per cent, of 

 the original leaves. 



2. Oleandra (sp.). E. Indies. Leaves arranged in whorls of 

 5 each, two whorls placed close together, alternate, forming a 

 complex or double whorl of 10 leaves. Each such pair of whorls 

 placed about 2 or 2 inches distant from the whorls above and 

 below it. Divergence = T ^. 



3. O. neriiformis. Luzon. Leaves arranged in whorls of 6 

 each, placed two and two together, alternate, as in the preceding, 

 and distant from those above and below them. Divergence y 1 ^. 



4. O. (sp.). Whorls of leaves in pairs, alternate, each whorl 

 containing 5 leaves. Divergence = y 1 ^. 



5. O. (sp.). Khasya Hills. Whorls of leaves in pairs, alter- 

 nate, each whorl containing 5 leaves. Divergence = y 1 ^. 



6. O. Wallichii. Nepaul and Assam. Whorls of leaves in 

 pairs, alternate, 5 leaves in each whorl ; the pairs of whorls are 

 3 inches apart. Divergence = y 1 ^. 



From the preceding facts we may infer that the whorled 

 species of Oleandra are probably constructed on two types of 

 whorls (56), both of which, by suppression of leaves, as 

 already explained, may be reduced to the phyllotaxis of alter- 

 nate-leaved plants. 



7. Aspidium Filix mas. Britain. In this Fern the rootstock 

 exhibits an arrangement of leaves and leaf-scars, alternate, 

 7-8 in each whorl, as is well shown in the ' Annals of Nat. 

 History/ December 1859, PL X. fig. 9. 



In the Ferns and Club-Mosses, the whorled arrangement of 

 leaves, although following the usual law, appears to be insuffi- 

 cient to produce the division of the stem into nodes, as happens 

 in the Equisetacese and some other natural families. 



The next case to which I would direct attention is that of the 

 Casuarinete, represented by an old-fashioned genus, Casuarina, 

 mostly confined to Australia and Tasmania, though it has 



