THE NAUTILUS. Tih 
Nation runs from 5 to 18 inches, but the variation by months or 
years shows a wide range, varying from one-half to twice the 
average. Over one-third of the rainfall may be credited to July, 
August and September ; about 12 per cent. to April, May and 
June. 
( To be continued) 
ON THE MARINE MOLLUSCA OF STATEN ISLAND, N. Y. 
BY ARTHUR JACOT. 
During the past summer I was enabled to continue a study 
of the shells to be found along the southeast shore of Staten 
Island working beyond the region reported upon in the January 
(1919) number of ‘‘ THe Nauriuuvs.”’ 
A week was spent at Great Kills Bay and vicinity. This bay 
was formed by asand-spit dropped by the lower New York Bay 
waters as they struck the current of the Kills which flow out at 
this point. Though half a mile narrower than its width (one 
mile), the bay is very shallow; the upper section, enclosed by 
high grasses except at the base of the sand-spit, is but two feet 
deep at low tide and covered with eel-grass, while the lower 
section is lined on the land side with cottages, hotels, piers, etc., 
is free from eel-grass, averages six to seven feet deep at low tide 
and is choked with launches and oyster boats. Throughout its 
extent, the bottom is formed of a soft, sticky clay, which mixes 
readily with the water. Due to this clay, the number of gaso- 
line boats, and possibly the sewers near the entrance, the mol- 
luscan fauna consists of the hardiest species only. 
Although we diluted and strained clay for hours at a time at 
the stations indicated, we found very few species. At one 
locality, dug-up clay mixed with a little sand yielded shells 
which from their leached-out appearance might be considered 
fossil. These fossil shells were much more numerous than those 
found above them on the surface. Barnea truncata, whose 
valves I have found in abundance lying on the bottom of the 
upper part of the bay a year and a half before, was not noticed. 
