in the Lycopodiacese, Equisetacese, &c. 439 



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

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

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

 have examined, the Oleandra presents the most marked examples 

 of the whorled structure. 



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

 examined 4—5 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- 

 dudendra. 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 | : 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 = ~. 



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 -^^. 



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

 containing 5 leaves. Divergence = jq. 



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

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



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

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

 3 inches apart. Divergence = -^q- 



From the preceding facts we may infer that the whorled 

 species of Oleandra are probably constructed on two types of 

 whorls (5-6), 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, PI. 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 Equisetaceai and some other natural families. 



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

 Casuariticce, represented by an old-fasliioned genus, Casuarina, 

 mostly confined to Australia and Tasmania, though it has 



