376 
a deposit which seemed identical with that forming 
in the pool, the ripple-marks being represented by 
undulations of the laminae. A remarkable feature 
of the section was the coincidence of the ripples 
through a vertical space of about eighteen inches. 
All the laminae were inflected in the same way, so 
that the corresponding parts of the undulations fell 
in the same verticals, as illustrated in fig. 1. 
It occurred to me, that there might be in this fea- 
ture something analogous to the assumption of stable 
L WY, LD 
ELL ty). Y WY) Mey D 
LYS, Wy YY iy re. 
By Yj, Wifi) Dr 
LES 
Be ee er Se 
Fie. 1. 
figures by free particles on the surface of a vibrating 
plate, and that the development of this idea might 
lead to a better theory of the origin of ripple-marks. 
The common theory, which makes the ripple-mark 
the homologue of the sand-dune, implies a forward 
movement of the ripple in the direction of the water- 
current, and is manifestly inapplicable to the phe- 
nomenon just described. I am disposed to doubt its 
applicability even to ripple-marks produced by cur- 
rents; for there is a certain class of these, intimately 
related to small obstructions, which are certainly as 
stationary and constant as the water-waves on the 
rapid of a stream. 
The analogy of ripple-marks to vibrations in elastic 
SCIENCE. 
14" 
= Cre 
[Vox. III., No. 60. 
ets 
fully drawn from hand specimens, Figs. 2 and 3 are 
the prevalent forms. In fig. 3 the crest is acute, and 
the broadly curved trough is midway between the 
crests. In fig. 2 the crest and trough are moderately 
acute, and the trough is nearer to one crest than to 
the other. In fig. 4 the crest is broadly curved, and 
the trough is less so. In fig. 5 each ripple has a sub- 
sidiary crest upon one slope. The resemblance of 
this last to certain phonographie curves suggests 
itself atonce. In other specimens two systems of rip- 
ples co-exist, intersecting at various 
angles ; and the fact that this relation 
was observed repeatedly, leads me to 
think that the two sets were syn- 
chronously formed. If synchro- 
nously formed, there is something 
in their production analogous to the 
co-existence of independent and di- 
i , aimee 
Gio verse vibrations in elastic bodies. 
= ED I do not venture to assert that the 
correspondences here pointed out 
are more than superficial analogies, 
but they suggest a line of investiga- 
Y 
57 : 
I, #1 ~~ tion which should be fruitful. Such 
ase investigation I had intended to 
= undertake, and the accompanying 
figures were engraved in pursu- 
ance of this intention; but, having 
found myself for some years unable to pursue the 
subject, I despair of commanding the necessary time 
and facilities, and avail myself of this opportunity to 
communicate my observations to the scientific public, 
in the hope that they may assist in the elucidation of 
the subject by another. G. K. GILBERT. 
The ‘Batrachichthys.’ 
The publication of the Archivos do museu nacional 
of Brazil began in Rio de Janeiro in 1876. In the sec- 
ond issue, that for the second and third trimesters of 
1876, the director of the section of zodlogy and com- 
parative anatomy in the museum published a descrip- 
Fig. 2.— Natural size. 
co ——r in |! I LM 
Fie. 3.— Two-thirds natural size. 
| | a 
ied 
= ] 
Fie. 5.— Natural size. 
bodies is further illustrated by variations in the forms 
of the ripples, and by the combination of sets of 
ripples. The other figures show in profile four 
forms of ripple observed on upper surfaces of triassic 
sandstone in south-western Utah. They were care- 
tion of what he denominated ‘an extremely curious — 
little animal called Batrachichthys’ The author 
evidently believed he had found a ‘ missing link,’ and, 
as it were, he laid his prize at the feet of Darwin, 
Haeckel, and Martius with the greatest solemnity. 
