TRANSACTIONS OF THE SECTIONS. 65 
he argued, was too small to belong even to the newly hatched young of the species 
I. Mantelli. Besides this, the skull showed that his new species had teeth in the 
front of the mouth of a conical and prehensile character, which the well-known 
species has not. The author further stated that he has discovered several other 
almost perfect skeletons of Iguanodons similar in size to that to which the small 
skull belonged ; and that all these remains came from different parts of one and 
the same bed in the Wealden formation near Brixton, in the Isle of Wight. The 
number of these small specimens, unmixed, as it seems they were, by bones of 
larger individuals, he assigns as another reason for regarding these bones as indica- 
tive of anew species. It appears also that this new species had four toes in the 
hind foot, whereas (if Owen fas made no mistake) the large Iguanodon had but 
three. Again, the new species, if it be such, has its iliac bones much more ex- 
* panded and bird-like than the same bones in J. Mantelli. And lastly, the author 
argued that the bones of these small specimens cannot have belonged to the young 
of the Iguanodon Mantell, because he has specimens where he can see in situ liga- 
mental bones stretching between the neural spines of the vertebre ; for, so far as 
we know, the ligaments of animals never become ossified till they have attained 
to considerable age. It appeared also from this paper that the author had made 
a vast accumulation of Ieuanodon bones and teeth of various sizes, and from these 
he is led to believe that not only is the small Iguanodon in question a new species, 
but that there were probably several species of the Iguanodon family existing at 
the time when the Wealden formation was being deposited. 
On the inapplicability of Fossil Plants to support the Theory of Gradual 
Transformation, By Professor Goprenrr. 
Artificial Rocking-stones, an experiment. By W. R. Grove, F.RS. 
Some short time ago, during an excursion in Cornwall, the author’s attention 
was naturally directed to rocking-stones, and those approximations to rocking- 
stones which are seen in the granite where it is exposed to the action of heat and 
cold, air and water. It need hardly now be contended that rocking-stones are na- 
tural results, and not superposed on their pedestals, as was once believed, by the 
hand of man. 
Throughout the greater part of the granitic rocks of the west coast of Cornwall 
formations are to be seen approaching in character to rocking-stones or to discoid 
piles like the Cheesewing. 
If we suppose a slab of stone of a parallelopiped form lying on another, both 
having flat surfaces—or, in other words, such slabs as are formed by fissures in 
horizontal and perpendicular directions, which are common in exposed granite 
rocks—the attrition and disintegration produced by changes of weather, of tempe- 
rature, &c., would necessarily act to the greatest extent at the corners, and next to 
that at the edges, because these parts expose respectively the greater surfaces com- 
pared with the bulk of the stone. This would tend to round off all the angles and 
gradually change the rhomb, more or less towards an oblate spheroid. This would 
account for the Cheesewing &c. But then, it may be asked, why should this pro- 
cess gradually work on to a rocking-stone ? in other words, why should the last 
unworn point, points, or line be in the line joining the centre of gravity of the 
appr stone with that of the earth ? 
Such an accident, it may be said, might happen, but the chances are almost 
infinity to a unit against it. Not so. Assume the wearing away between the 
slates to reach a point which is not in the line of centres of gravity: the upper 
stone would then fall on one side, leaving the unworn point most exposed to cli- 
matal and probably to electro-chemical action from the water lying in the angle 
of the crevice, evaporation being less rapid there than at other parts. This pomt 
would then be worn away and the stone would fall back a little, then fresh action 
upon new surfaces, another oscillation, and so on. The effects above explained as 
talking place by steps would in fact take place by insensible progression. As- 
- suming this process, unless there be some interfering action, it hecomes not impro- 
1868. 5 
