HARDWICKE'S SCIENCE-GOSSIP. 



27 



however, are very frequently false bedded, that is, 

 are of what has been termed " eolian origin," and 

 indicate a shallow drifting sea. Now, as far as my 

 experience goes, these beds almost invariably indicate 

 a southerly set of the sea, and this, I believe, has 

 been pointed out by Professor Rupert Jones. Now this 

 southerly set being assumed, it is self-evident that all 

 drifted material must come from the north, and this 

 (curiously enough) is exactly the direction in which 

 the ancient rocks are now known to lie. Thus we 

 see how facts which appear so trivial in themselves 

 fall in with others in a most unexpected manner. 

 The pebble-beds may be examined in several of the 

 hollow lanes around Godalming, but perhaps the 

 most instructive are to be seen in the lane leading 

 from Farncombe to Northbrook, and also in the new 

 road cut some few years since along the southern face 

 of Frith Hill. Starting from near the Godalming 

 Cemetery, we first come upon the greyish sands of the 

 Sandgate division, traversed in every direction by 

 white calcareous veins of various widths. 



A little higher up we have a good series of pebble- 

 beds, in which many fossils occur ; here the beds are 

 soft, and not cemented into a hard concrete as in 

 some sections. Still higher we come on the false 

 bedded sands, alternating with bands of poor Bargate 

 stone. Higher still a sparse seam of pebbles occur 

 with a few teeth, and then alternate bands of Bargate 

 and sand, the latter with broken terebratulce in 

 abundance. In one of the last-named beds some 

 fossil wood was found in a very peculiar state of 

 preservation ; it is chocolate-brown in colour, but 

 when rubbed between the finger and thumb goes to a 

 fine unctuous powder. This wood is of course not 

 extraneous, but I have no doubt of its really being a 

 fossil, having lately received some from the Holloway 

 Hill Pit actually embedded in a piece of Bargate 

 stone. I mention it here the more willingly, seeing 

 that the occurrence of wood in any strata seems to 

 indicate the existence of a land surface in greater or 

 less proximity, and it would be interesting to know 

 whether the ancient crest of rocks did, or did not, 

 support a terrestrial flora. Returning to the pebble- 

 beds : in a few hours' collecting one may have the 

 good fortune to find many of the following. Firstly 

 there are the scales and teeth of Lepidotus. The 

 former are usually somewhat lozenge-shaped, thick, 

 and beautifully enamelled — a good example of ganoid 

 scales. The edges of the opposite side have a parallel 

 bevel. One scale, however, I possess, probably refer- 

 able to this genus, is thin and oblong in figure, the 

 lines of growth being distinctly visible. The teeth 

 of Lepidotus, which frequently occur, are mostly hemi- 

 spherical, and shine in the bank like small gems. 

 Pycnodus and Gyrodus, and the conical Saurichthys 

 are also ganoids. Among the placoids (which by the 

 way are more angry-looking teeth) we have the 

 thorn-like teeth ofLamna. Of Hybodus several forms 

 occur, and likewise the spines or fin bone. Acrodus 



and Notidanus nearly complete the list, though there 

 are still a few which have not been identified. In 

 conclusion I should only mention that the pebble-bed 

 may be examined at Redcliffe, in the Isle of Wight, 

 where it consists of rounded and subangular pebbles 

 of quartz, and associated with water-worn fragments 

 of wood and bone, and various drifted fossils. It 

 occurs near Dorking, below the "fuller's earth " at 

 Nuffield, as also near Sevenoaks and Maidstone. To 

 the west of Godalming we find its equivalent in the 

 "sponge gravel" of Faringdon, Berkshire, in certain 

 beds near Devizes, and probably further northwards, 

 in the phosphate beds at Upware, near Cambridge, 

 and in the lower beds of the greensand of Hunstanton 

 in Norfolk, as stated by Mr. Meyer. 



H. W. K. 



A 



NOTES ON PHYLLOTAXIS. 



By H. Walter Syers, M.A. Cantab. 



VERY important part of structural botany is 

 that which is concerned with the arrangement 

 of the leaves with regard to the stem or axis which 

 bears them. It must be tolerably clear to any observ- 

 ing person that in this matter of leaf arrangement 

 things do not go by hap-hazard. On the contrary, 

 the whole subject is governed by rigid and somewhat 

 complicated mathematical principles, and it is the 

 object of this paper to briefly point out the most im- 

 portant laws governing the arrangement of leaves on 

 the axis. This branch of botanical science is termed 

 Phyllotaxis (<pv\\oi>, r a leaf, rd£is, arrangement), and 

 before going farther into the subject it will be neces- 

 sary to state that the point of the stem from which the 

 leaf proceeds is called a node, the leaf being developed 

 as a cellular process connected with the vascular 

 bundles of the axis. The space intervening between 

 any two nodes is termed an internode. Now there 

 are three principal modes of leaf arrangement : 



1. That in which the leaves are placed at different 

 levels alternately round the axis. This is alternate 

 phyllotaxis. 



2. That in which the leaves are placed in pairs, at 

 the same level, and opposed to each other. This is 

 opposite phyllotaxis. 



3. That in which the leaves come off at the same 

 point in the axis, three or more arising from the cir- 

 cumference of the same circle, and assuming a whorled 

 or verticillate arrangement. This is verticillate phyllo- 

 taxis. 



The alternate leaf arrangement is the one that 

 requires most consideration, it being, as it were, the 

 foundation of the whole system, and from which the 

 others diverge more or less. It is likewise one of the 

 most ordinary forms, being the normal arrangement 

 in Monocotyledons, and being extremely common 

 amongst Dicotyledons. The leaves in this case are 

 disposed round the axis, more or less, in a spiral 



c 2 



