548 
NATURE 
[ Oct. 8, 1885 
to the energy evinced by the waves in the particular instance 
under consideration. 
Having learned from Lord Rayleigh that wave-action at the 
sea-bottom takes the form of reciprocal currents, I was led to 
make some experiments and observations on the formation of 
ripple-mark. In the course of this investigation I was soon 
impressed with the conviction that these alternate currents held 
at their mercy the marine fauna exposed to their attacks, and 
that the zoological side of the problem was at least as important 
as the geological. Accordingly, an outline of the subject in its 
zoological aspect was included in a paper on ripple-mark read 
to the Royal Society in 1882 (Proc. R.S., vol. xxxiv. p. 1). 
Having come into possession of confirmatory evidence of the 
action of waves at a depth of forty fathoms in the English 
Channel, I submitted the facts to the British Association at 
Southampton in the same year, 1882. This paper, sent in to 
Section A, was handed on to Section C, a mathematical friend 
suggesting to me the reason, and a very good reason too, that 
mathematicians required no evidence on the point contended 
for. However, the transfer only went to prove that the geo- 
logists were as sceptical as to the existence of wave-action at 
forty fathoms, as the physicists were satisfied as to that fact. 
This paper, amplified, appeared in the Zyvavsactions of the 
Devonshire Association for 1883 (vol. xv. p. 353). 
The zoological aspect of the question was submitted to the 
British Association at Southport in 1883; and again to the 
Linnean Society in 1884, in a paper ‘‘On the influence of 
wave-currents on the fauna inhabiting shallow seas.”” In this 
paper, profiting by experience, I made no attempt to prove the 
fact of wave-action from observation, but relied entirely on a 
valuable letter with which I had been favoured by Prof. Stokes, 
Sec.R.S. Neither at the British Association nor at the Linnean 
Society was any exception taken to my arguments in support of 
the importance of wave-action on the fauna affected ; nor, so far 
as I am aware, has my position been shaken since. Now that 
Prof. Moseley’s important lecture has appeared, discussing the 
fauna of the sea-shore without reference to the ever-regulating 
wave-currents, there is considerable risk that less experienced 
students of natural history will in like manner pass over this 
promising field of research as not worthy of their attention. 
Prof. Moseley states, and states truly, that the littoral fauna 
is adapted in various ways to withstand ‘‘the action of the surf, 
the retreat of the tides, the numerous enemies”; but, beyond 
the reach of surf and tidal fall, agents which only affect the 
narrow belt of sea contiguous to the shore, the alternate currents 
set up by ocean waves search out the armour and test the 
defences of all small animals living on those extensive marine 
areas, exposed to the ocean swell, where the depth of water does 
not exceed fifty fathoms. 
With respect to enemies, the waves themselves are perhaps 
the most formidable, as they attack and occasionally destroy 
whole colonies at once, whereas predatory foes rather affect the 
individual. For instance, let such helpless mollusks as Alysia 
or Pleurobranchus wander over the sandy bottom of Torbay, as 
they sometimes do: the first easterly gale will sweep them out 
of existence. In fact, the waves so invariably prevent 4flysia 
punctata growing to its full size on the British coast, that a full- 
grown specimen taken in protected Guernsey waters has been 
considered a distinct species—viz. A. defilans. Similar large 
specimens have occurred under the shelter of the Torquay har- 
bour works, but these, by a series of odontophores and shells, I 
have been able to connect with the common 4. punctata, 
Prima facze it would appear that the shells of certain mollusks 
are more especially adapted to resist animate foes; but a close 
examination will often prove the contrary. Take the cases of 
the oyster, mussel, venus, and limpet: these mollusks are all 
helpless in the presence of their living enemies: the oyster 
perishes by the attacks of boring-sponges ; the mussel is de- 
stroyed wholesale by starfishes ; the venus is perforated by car- 
niyorous gastropods at their leisure; whilst the limpet, easily 
detached when taken unawares, is said to be destroyed by birds. 
All four are, however, admirably adapted to resist wave-currents, 
each in its respective habitat. 
The conclusion that the shells of mollusks are so constructed 
as to have comparatively but little reference to living foes is 
supported by the interesting fact mentioned by Prof. Moseley, 
that hard shells tend to disappear in pelagic and deep-sea regions. 
That is to say, they disappear where predatory enemies abound, 
but where the great non-predatory enemies, the waves, are 
powerless or not existent. Occasionally we find the supposed 
protection against living enemies to be greatly in excess of 
requirements—e.g. the case of the solen, whose power of burrow- 
ing is far greater than requisite for escape from birds, but which 
is none too great for the evasion of waves and currents tearing 
away the sand in which the mollusk dwells. 
Wave-action tends to differentiate species. This can be seen 
in such obvious cases as Cardium aculeatum and C. norvegicum, 
Venus dione and V, chione. One of each of these pairs has 
chosen the mooring method of defence with anchor-like spines, 
the cther that of facile penetration with smooth, unresisting 
shell surfaces. As these two methods are opposite in action 
and any compromise tends to inefficiency, the wave-currents 
must necessarily influence the mollusks in the direction of 
divergence. 
Instances of habits and forms protective against wave-currents 
could be multiplied almost ad infinitum, and, as the subject is a 
very interesting one, I still live in hopes that it may yet be 
taken up and worked out by trained observers qualified for the 
task. ARTHUR R. Hunt 
Torquay, September 28 
Prehistoric Burial-Grounds 
THE account given in this week’s NATURE (p. 518) of the dis- 
covery of a prehistoric burial-ground at Pitreavie has recalled 
to my memory the description of a similar find made in the 
eleventh or twelfth century by the monks of Noyon, and related 
to us us by Guibert, who was abbot of this foundation at the 
time. I believe that it is the earliest detailed account of any 
such discovery that has come down to our days ; and it will be 
noticed that the leading features of this cemetery are almost 
exactly identical with those of the Pitreavie one. I am not 
aware that this passage has attracted the attention of modern 
writers upon prehistoric times. 
Guibert, the author quoted, was born in 1053 and died in 
1124, having been Abbot of Noyon for about twenty years. 
After stating his own conviction that his monastery was 
extremely old, he continues :— 
**Quam opinionem, si nulla litteralis juvaret traditio, sup- 
peteret profecto affatim peregrina, et non, putamus, Christiani 
nominis sepulchrorum inventa contextio. Circa enim ipsam et in 
ipsa basilica tantam sarcophagorum copiam conjunxit antiquitas, 
in multam loci famositatem tantopere expetiti, cadaverum inibi 
congestorum commendat infinitas. Quéa enim non tn morem 
nostrorum ordo adisponitur sepulchrorum, sed circulatim in 
modum corolle sepulchrum unius multa ambiunt, in quibus 
| gquedam reperiuntur vasa, quorum causam nesciunt Christiana 
tempora. Non possumus aliud credere nisi quod fuerunt 
gentium, aut antiquissima Christianorum, sed facta gentili more.” 
GuIBERT!I Novig. de Vita Sua, L. ii. cap. 1. 
I may add that in Guibert’s time there was a very old written 
tradition which ascribed the foundation of Noyon to a certain 
‘rex insulze Britanniz,” who was (so ran the legend) a con- 
temporary of our Lord’s. This tradition is, of course, worthless 
from a historical point of view, but certainly testifies to the 
extreme antiquity of the place; and shows that, long before 
Guibert’s time, the inhabitants of Noyon had dim recollections 
of their prehistoric greatness, which naturally, in an age of 
Christian credulity, centred around the era of our Lord. 
T. A. ARCHER 
158, Walton Street, Oxford, September 30 
MARS, {UPITER, AND SATURN 
XN} 71ITH Mars, Jupiter, and Saturn in the morning sky 
VW i 
the telescopist has a varied assortment of brilliant 
objects to which he may devote his attention. The great 
distance of Mars during the ensuing opposition will have 
the effect of limiting the apparent diameter to a low 
value, but the chief markings are so conspicuous as to be 
visible notwithstanding this inimical effect. Indeed 
during the preceding opposition, which was equally un- 
favourable, some of the more delicate features appear to 
have been recovered. At Milan Signor Schiaparelli has 
partly confirmed his previous results as to the singular 
duplication of the “ canals,” and Mr, Knobel has obtained 
