120 
ALASKA GEOLOGY 
A tube, presumably that of an annelid worm, is visible on the sur¬ 
face of one of the bivalves from Popof Island. 
SUMMARY 
The above list shows as the known fauna of the Miocene 
of Unga and Popof Islands, Alaska, thirty-one species of 
invertebrates, which more thorough exploration would 
doubtless much increase. The list shows: 
Species of No. 
Pelecypoda 22 
Gastropoda 8 
Annelida 1 
New. 
6 
2 . 
The present list adds about sixteen species to the num¬ 
ber of those known to exist in this horizon in Alaska. 
III. PLEISTOCENE FOSSILS FROM DOUGLAS ISLAND 
The space between Douglas Island, the mainland and 
a sand-bar extending across the channel from the island 
northward to the mainland, constitutes Juneau Harbor, 
Alaska, and its immediate approaches. The shores of the 
island rise steeply from the water and are covered with 
sand, mud and gravel to a considerable height. This 
material resembles that of the 6 Leda clays ? of the St. 
Lawrence valley or the marine Pleistocene deposits of the 
Maine coast. The geological features of this vicinity have 
been discussed by Mr. Gilbert in volume 111 of this series. 
It is only necessary here to state that on climbing the 
slope alongside of a trench which had been dug to con¬ 
vey water pipes from the upper portion of the island down 
the slope to the town of Douglas, I discovered that for a 
certain distance these deposits contained marine fossil 
invertebrates. These ceased abruptly at a height deter¬ 
mined by pocket aneroid as 200 feet above the sea-level 
at high water. It was evident that at the time of the 
deposition of this boulder clay and gravel the level of the 
