A. FE. Verrill—The Bermuda Islands; Geology. 199 
Some of the tubular forms may have been due to the consolidation 
of the walls of the burrows of animals, such as the land-crabs, earth- 
worms, etc. 
Synopsis of Bermuda Paleontology. 
Three distinct formations can be distinguished by their fossils: 
Ist. The earliest rocks now visible above the sea probably belong 
to the Pliocene. They are here designated as the Walsingham 
Formation. They contain at least 17 species and 6 varieties of land 
shells (Pulmonata), of which 9 species and 4 varieties are extinct, 
besides one that still lives in the West Indies and southern United 
States, but not in Bermuda (Strobilops Hubbardi, fig. 53). 
This formation contains all the known species (6) and most of 
the subspecies or varieties of Pecilozonites, a genus peculiar to 
Bermuda. This genus had already attained its greatest develop- 
ment at that early period, for the largest and strongest species 
(P. Nelsoni), now extinct, was then very abundant, and all the 
other species and varieties were larger and heavier than their modern 
descendants. 
In view of the great development of this genus at that time, it 
might well be called the Pecilozonites Period. 
No marine deposits of this age are visible, for it was followed by 
a subsidence of 100 feet or more. 
2d. The second formation, here called the Devonshire, is composed 
in part of marine limestones or ‘beach rock,” containing a large 
number of marine shells, corals, foraminifera, etc. It corresponds to 
the period of greatest subsidence. The marine limestones are now 
rarely elevated more than 8 to 12 feet above the sea and extend 
below low tide in some places. They have suffered greatly by ero- 
sion, and are now often of small extent. olian rocks of the same 
age occur. The marine fossils are mostly species still living in Ber- 
muda waters. A few (about 10) are now extinct there (p. 189), but 
most or all still exist in the West Indies. 
This period probably corresponds precisely with the Champlain or 
Leda-clay period of New England and Canada. It was followed by 
a period of elevation, probably of small amount (at least 12 feet, 
and perhaps 25 feet or more). 
3d. The third formation, here called the Paget, was the period of 
reélevation, probably to a height somewhat greater than the present. 
It consists chiefly of wxolian limestones, unconsolidated shell-sands, 
