Pleistocene History of Fishers Island —Fuller 5 1 
not appear till the colony begins to branch. Hemisepta have 
not been seen in any of the earlier zooecia. These studies 
seem to definitely relate Fenestella genetically to the Cyclos- 
tomata. The Cyclostomata are therefore the ancestors of 
the Cryptostomata and through them of the Chilostomata. 
PLEISTOCENE HISTORY OF FISHERS ISLAND, N. Y.* 
Myron L. Fuller, Washington, D. C. 
Fishers island, which is located several miles southeast 
of New London, Connecticut, is not, as has been previously 
supposed, a simple morainal island. On the contrary the 
morainal deposits of the last, or Wisconsin, ice invasion, are 
generally only a very few feet in thickness, the great mass 
of the island being made up of material deposited during 
earlier ice advances or interglacial stages. The oldest for- 
mation definitely recognized on the island is the thick bed of 
clay which is well exposed at the big clay pit. This merges 
upward without unconformity into a series of sands and fine 
gravels, the whole being later thrust up into folds of consid- 
erable hight. The folded deposits were subsequently deeply 
eroded, but were covered again up to a certain altitude by 
horizontal sands and gravels deposited during a later ice in- 
vasion. These were in turn eroded by streams before the ad- 
vent of the last ice sheet, w^hich left a thin mantle of till and 
otherwise slightly modified the surface at certain points. 
The various formations are correlated with similar beds on 
Long island on the west, and on Block, Marthas Vineyard 
and Nantucket islands on the east. The clay and the over- 
lying conformable sands are assigned to the Yarmouth inter- 
glacial stage, the folding to the Illinoian. and the horizontal 
(Tisbury) sands to the lowan glacial stage. 
* Abstract of a paper read at the Philadelphia meeting. G. S. A., 
Dec. 1904. 
