342 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
by Dr. Friedrich Schmidt. The other view appears to have been 
first broached by Hisinger. According to him, the strata of Gotland 
are essentially horizontal with only a slight dip to the east, so that 
the same beds are found over many parts of the island. This view 
received strong support from Helmerson, F. Roemer, Angelin, Bather, 
Stolley, Wiman, Dames, and Lindstr6m. 
Among the latest published studies of the stratigraphy of Gotland 
are those from the pens of Drs. Henry Munthe and Herman Hedstrém, 
the former having studied the southern and the latter the northern 
half of the island. With some modification, Munthe appears to be in 
general agreement with the second view, while Hedstrém appears to 
adopt the views of Murchison and Schmidt with, however, considerable 
changes. 
In general, the strata of Gotland have been said to fall into two 
lithic divisions; a lower, consisting of calcareous shades, thin lime- 
stones, odlite, and sandstones, and an upper, consisting of coralline 
and crinoidal limestones with subordinate shales. This grouping has 
been previously noted by Holm, Munthe, and others. It has generally 
been considered that the boundary between the two divisions is fairly 
sharp, but it is by no means certain that such is the case, since much 
which has been considered evidence of sharp division is capable of 
a different interpretation. 
The detailed work of Munthe over the southern part of Gotland 
has given the classification which follows. The divisions are named 
from the summit downward. 
la Ascoceras limestone. 
1b Youngest crystalline limestone. 
Ilionia or Spongiostroma limestone. 
Upper Sphaerocodium bed and odlite. 
Sandstone with clay. 
Lower Sphaerocodium bed. | 
Dayia flags. 
Marl shale with lenses and bands of limestone. 
“IO OP W bO 
For northern Gotland Hedstrém has offered the following sub- 
divisions, named in order from the highest to the lowest. 
VII. Nonstratified reef limestones or stratified crinoidal and coralline 
limestones. 
VI. Leperditia shales. 
V. O6litic limestones. 
1 Munthe. Guide book 11th. internat. geol. congr., 1910, no. 19, p. 49-50. 
