THE - CONCHOLOGISTS 
EXCHANGE. 71 
Young Collectors’ Corner. 
Some Remarks on the Migration of 
Mollusks. 
BY JOHN FORD. 
Philadelphia, Nov., 1887. 
It is hoped that the students who have vis- 
ited this corner for the purpose of collecting 
something worth ‘retaining; have also found 
much that is interesting and instructive in Mr. 
Simpson’s article on the “ Distribution of Land 
and Fresh Water Shells in the Tropics,’’ which 
appeared in the last two numbers of THE Con- 
CHOLOGISTS’ EXCHANGE. ‘The theories ad- 
vanced in this article are certainly among the 
best that have been offered on the subject. 
That many species have been transported by 
natural means across deep and wide seas is a 
fact that is generally acknowledged, but of the 
vehicles of their distribution in the remote eras 
alluded to, scarcely anything is positively 
known. 
There seems little doubt. however, as Mr. 
Simpson suggests, of the uprooting of vast for- 
ests in the latter part of the Tertiary period, 
when plutonic forces were rending the earth 
almost continuously, and of their being driven 
by strong water-currents or mighty tempests far 
from their native regions. It is well known that 
such changes are of frequent occurrence even 
now, when the earth, comparatively speaking, is 
resting from her labors. 
Thus it is easy to comprehend the tearing up 
and sweeping away, during the period of seis- 
mic disturbances referred to, of myriads of 
sturdy trees, among the boughs and roots of 
which numerous species of mollusks made their 
homes, — 
One may therefore readily believe that num- 
bers of these “Giants of the primeval forests” 
were often massed together, with their extremi- 
ties so interlaced as to leave some of each en- 
tirely unsubmerged during the period of drift; 
and that on many occasions both land and fresh 
water Shells were safely ferried from continent 
to continent, as well as from island to island. 
In such an event, too, the journey could be 
accomplished without much discomfort to the 
passengers, as certain fresh water species will 
live for months without food or drink, while 
many species of helix will endure the same 
apparent hardships for years, as I have good 
reason to know, having on one occasion found 
a number of Syrian species alive and active 
when taken from the box-prison in which they 
had been packed with dry sand, on the Arabian 
desert, quite two and a-half years before. In 
each case the usual air-tight curtain had been 
stretched across the aperture of the shell, but a 
drop or two of water quickly dissolved this, and 
a few minutes later the animal awoke from its 
deathlike sleep as fat and vigorous as though 
only a night had passed since its incarceration. 
In recent times the advent,of species on 
shores foreign to their habitat is more easily 
explained, For instance:. a fine specimen of 
Litiopa striata, Rang, a species peculiar to the 
Coast of Florida, was found a short time ago 
on a Rhode Island beach by Mr. H. F. Car- 
penter, of Providence. 
That it was carried north by the Gulf stream 
and stranded by a fayorable wind there can be 
no doubt, as Mr. Tryon states in his work on 
“Structural and Systematic Conchology,” that 
“they occasionally suspend themselves from 
the stems of floating sea-weed,” a condition 
exceedingly favorable to transportation in the 
way indicated. 
Mr, Carpenter also secured, about the same 
time, a magnificent helix which had been found 
some days before in a grove a few miles from 
Providence. The shell was an inch or more 
in diameter, and of dark brown color, the ani- 
mal being intensely black and shining, and 
crowned with a pair of “horns” fully an inch 
in length. Being unlike anything native to 
Rhode Island, and unknown to him, Mr. Car- 
perter at once forwarded it to the Philadelphia 
Academy of Natural Sciences for comparison. 
Here it Was readily identified as Helix alauda, 
Fer., although larger, finer and blacker than 
any of the thirty or more spécimens in the col- 
lection, all of which had been captured in the 
Island of Cuba, where the species strictly be- 
longs. 
It follows then, that this specimen must have 
reached Rhode Island through human agency, 
the most likely vehicle being a bunch of ba- 
