THE NAUTILUS. 



Nation runs from 5 to 13 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 NAUTILUS." 



A week was spent at Great Kills Bay and vicinity. This bay 

 was formed by a sand-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. Baraen truncala, 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. 



