THE NAUTILUS. 113 
Alectrion trivittata (Say) common. 
Eupleura caudata (Say) few. 
Urosalpinx cinerea (Say) occasional. 
The sod-bank or Modiolus demissus association was to be 
found on any clay or hard-mud bank exposed between tides. 
This association consists principally of Modiolus demissus pli- 
catulus packed tight one against the other or separated by 
Mytilus edulis packed just as closely, over both of which crawl 
Tatorina littorea and L. rudis. Modiolus demissus demisaus is found 
very thinly scattered among the individuals of the northern 
form. That the southern variety was once the predominant 
form over this area is evident from the fact that the sod banks 
on which plicatulus is now living contain the dead valves of the 
southern form exclusively, in large numbers and buried to a 
depth of 8 or 10 inches below the surface in company with Mya 
arenaria. I do not think the two forms interbreed. 
Half a mile southeast of the bay where there is a stone jetty 
running out into water four to five feet deep at low tide, the 
rocks and bottom were searched but with very discouraging re- 
sults. The water all along this section of the island is heavily 
laden with fine mud from the red dirt characteristic of that part 
of the island. This we believe to be the reason for the scarcity 
of mollusca along the beaches southeastward. A shattered but 
uneroded and still united pair of valves of Modiolus modiolus 
(Linné) were found at Seaside Beach. 
Our survey of the island showed the north and northeast 
shore of the island to be rocky and built over by commercial 
interests. From Fort Wadsworth to Prince’s Bay (the south- 
east cost) there are sandy beaches interrupted by sod-banks. 
As one progresses southeastward these beaches become more 
and more rocky to Prince’s Bay, from which point and around 
the southern end of the island the shore is characteristically 
rocky. The remaining (western) coast line is lost in a maze of 
salt marsh. Thus there are but two places along the southeast 
coast of Staten Island where Mollusca are of special interest, 
namely, the sand flats between South and Midland Beaches and 
the complex about the base of the Great Kills Bay spit. The 
southern end of the island was not studied. 
