I2O 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. New. 



Pelecypoda 22 6 



Gastropoda 8 2 



Annelida I 



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 ' 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 in 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 



