38 
THE ; CONCHOEOGISTS’ = EXCHANGE. 
such a mighty forest on the mainland of Hon- 
duras. I never until then realized how utterly 
insignificant and powerless I was in the pres- 
ence of Nature. But this is a digression. Such 
a forest is the natural home of hosts of the 
arboreal tropical land snails, the Bulimi, the 
Achatinas, Orthalicus, Liguus, some of the 
Helices and many others. Among these aerial 
gardens every variety of food and shelter is 
provided that they can possibly need. 
During the rainy seasons of the tropics, thou- 
sands of such trees with their immense collec- 
tions of vegetable and animal life are under- 
mined by rivers and torrents and carried out 
into the sea. Nor is this all. From Cape St. 
Roque along a vast stretch of the South 
American coast far to the northward, and at 
many points in the West Indies and the main 
land of Central America, the sea is constantly 
encroaching on the land, undermining and 
carrying away millions of acres of this virgin 
forest. I have seen hundreds of acres of such 
trees on the coast of Honduras slowly toppling 
into the sea. Many of these carry not only 
all their arboreal mollusks with them, but with 
the tons of soil, undergrowth and shrubbery 
which adhere to their roots, a great variety of 
terrestial species. Such rafts of floating vege- 
tation are not unfrequently met with in tropical 
seas, and borne by ocean currents or carried by 
storms are often landed within a moderate 
length of time on other shores. In_ shelt- 
ered caves on the Island of Utilla and 
other of the Bay Islands, and on the shores of 
Florida, I have seen thousands of such 
stranded monsters, some submerged all but a 
few branches. others at the tide line, and still 
others thrown high and dry by storms, out of the 
reach of the sea at ordinary times. I conceive 
that many snails carried on the higher limbs of 
such trees, in the sheltering crevices of the 
Matapalos or among the rank epiphytal vegeta- 
tion might make such a sea voyage in safety, 
and being thrown high and dry in the edge of 
a forest in similar latitudes might find all the 
circumstances favorable for living and produc- 
ing an established colony in their new home. 
Especially would such mollusks as the Stro- 
phias. Glandinas, Truncatellas, Auriculas, 
Pythias and some of the Stenogyras, whose 
natural habitat is near the sea and which are 
sometimes exposed to its spray, be likely to 
survive such a cruise, and it is just such species 
that we find introduced in the greatest numbers 
in the warmer parts of the earth. Glandina 
truncata is an abundant shell throughout a 
great part of Florida, and it is also plentiful in 
Cuba, and no matter which country it was in- 
troduced to it has undoubtedly crossed the sea. 
So of Strophia incana, a Cuban species abun- 
dant on the Florida Keys, Stenogyra gracillima, 
several West Indian Truncatellas, and Auricula 
pellucens, all found plentifully in Florida and 
within the influence of the sea. Orthalicus 
undatus Liguus fasciatus, Bulimulus multi- 
lineatus and other species found on the south- 
ern part of the peninsula of Florida are arbo- 
real and have come from Mexico, the West 
Indies. and South America, ‘These species 
during periods of rest secrete an epiphragm 
by which they adhere with great tenacity to 
the branches and trunks of trees so firmly that 
the shell will often break before it will let go, 
and in many cases must be collected by care- 
fully cutting away the bark to which it adheres, 
This epiphragm seems to be impervious to the 
influence of wind, sunshine or moisture, and is 
only dissolved by the animal when it revives 
its activity. During such a period of zeestiva- 
tion it seems to me these snails might make 
such a passage at sea with little difficulty if they 
were borne above the crest of the waves. 
To be Continued. 
DESCRIPTION OF NEW GENERA 
OR SUB-GENERA OF HELICIDA. 
BY C. F.-ANCEY. 
( Continued.) 
XXVIL—Pleuroxia, Ancey. 
I propose the above name for Angasella 
(type: Helix cyrtopleura, Pfeiffer), as the latter 
name issalready pre-occupied in marine shells. 
Geog. distrib.: Central and Southern Aus- 
tralia. 
XXVIJI,—Calostropha, Ancey. 
