190 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of green and gray limestone and pieces of shale; and at Catherine 
Park, Reval, the green “Glauconitkalk”’ is likewise followed by a six 
inch layer of conglomerate in which there are pebbles of limestone 
full of glauconite. This unconformity is not newly discovered, but 
was distinctly foreshadowed in Schmidt’s papers, and was definitely 
worked out by Lamansky, who, however, placed the layers containing 
Asaphus expansus in the overlying formation instead of with the older 
strata, as the evidence seems to require. (Plate 2). 
The doubtful member of this formation is the green sand. It is 
placed here, because there is an undoubted break in the sedimentary 
record between the Dictyonema shale and the M. planilimbata lime- 
stone. In Norway and Sweden one finds between these two forma- 
tions the Ceratopyge limestone, with a fauna which, though it occupies 
no great thickness of strata in Scandinavia, really endured for a very 
~ long period of time. During this interval no deposition was taking 
place in the region in Russia here discussed, and, apparently, neither 
was there any great erosion, the district standing nearly at sea-level. 
Durmg some part of this time the green sand seems to have accumu- 
lated, perhaps as a beach sand, at least at first, but probably reworked 
as a whole or in part by the invasion of the sea in which were deposited 
the Walchow sediments. It differs from an ordinary beach sand not 
only in its green color, but in the presence of much fine clay. It 
usually shows neither stratification nor cross-bedding. The fauna isa 
scanty one. In the west, on the Baltishport peninsula and near 
Reval, a few specimens of Obolus lingulaeformis Mickwitz, a Lingula, 
a Siphonotreta and conodonts have been found. At Papowka, 
Lamansky has referred to the “Glaukonitsand” a sandy part of the 
limestone, and has obtained from it a considerable fauna which he 
considers to be distinct from the regular M. planilimbata fauna and 
allied to the Ceratopyge fauna of Scandinavia. This fauna is how- 
ever, too closely allied to the M. planilimbata fauna to indicate the 
presence of either a Ceratopyge or Lower Didymograptus fauna, and 
the strata containing it would seem to go naturally with the limestone 
rather than with the sandstone of the section. 
So far as I have seen it, the fauna of the green sand seems to be 
allied with that of the Ungulite sandstone below, rather than with the 
limestone above. The sand and clay content of the bed may easily 
have been derived from the denudation of the underlying Packerort 
formation, which was undoubtedly uplifted and subjected to erosion 
at some localities, even though we can not now point definitely to the 
particular places, and, such being the case, it seems more probable 
that the sand belongs to the later and not the earlier sedimentation. 
