1890.] NEW YORK ACADEMY OF SCIENCES. 17 
the centre, which in others was filled with calcareous material. 
I believe Dr. Dolley’s theory of the formation of these cylin- 
drical and tubular projections is, in the main, the correct one; 
for I collected specimens with the roots still in them, and the 
concentric arrangement shown on cross section shows very 
plainly that the solvent action of the water, following the path 
of the root, had been from within outward. As these masses are 
conspicuous and characteristic, I would suggest that they be 
called rhizomorphs ; and this name would also cover the tubular 
masses that have evidently been formed in the same manner, 
and which I have found in the ferruginous clays of New Jer- 
sey and elsewhere. ‘he action of the water in the latter case 
has been on the iron contained in the clay. 
Dr. Dolley is inclined to think that the rhizomorphs were 
formed while the sand was in a loose state; and while I do not 
deny that this might be possible, I believe that all that I saw 
had been formed by the roots penetrating the already hardened 
rock; and I furthermore found no rhizomorphs being formed 
by the plants growing in the loose sand. 
Dr. Dolley also states * that the ‘‘small islands exhibiting these 
peculiar formations ” (rhizomorphs) ‘‘ are indications, therefore, 
of erosion and subsidence.” I admit the erosion; but as the 
rhizomorphs are found twenty and thirty feet above the sea-level, 
I think that subsidence has taken no part in their formation. 
These rhizomorphs are not to be confounded with the cylindri- 
cal masses described on Goat Cay, for the latter were vertical 
and did not exhibit the concentric arrangement of the particles 
so plainly shown in the rhizomorphs, which are found at all 
possible angles. And if we suppose the masses on Goat Cay to 
be due to the same process that formed the rhizomorphs, we must 
suppose that the roots that produced them grew vertically down- 
ward, which is extremely improbable. It may be well to state 
that a few rhizomorphs were found on Goat Cay, and the differ- 
ence between them and the cylindrical masses was very marked. 
It might be asked, if these rhizomorphs have been formed 
in the manner described, why is it that we do not find them 
everywhere on the islands? And in answer to this objection it 
may be said that roots of most of the trees spread out over the 
ground or slightly under the crust, but do not penetrate the 
rock; and that the roots of the smaller plants are those that 
have formed the rhizomorphs, and that these latter show only 
where there is but little vegetation, and where the erosion is 
active and not helped by the roots of trees breaking up the sur- 
face into blocks as described above. 
1 Loe. cit., p. 132. 
