On the Naiades of Long Island, New York. 
N. M. GRIER, PH. D. 
The following species are cited as occurring in this region: 
Elliptio complanatus Dillwyn (1). Described as being mod- 
erately abundant at Riverhead ; Anodonta implicata Say (2, 3). 
Found in lake at Prospect Park, Brooklyn, and at Baisley’s 
Lake, Jamaica South; Anodonta cataracta Say (3), from Kis- 
sena Park lake, Flushing. The writer notes the occurrence of 
this species at Lake Ronkonkema, a glacial kettle hole lake 
near the center of the island, where it seems fairly common. 
This species is widely distributed over the Atlantic slope. A 
number of specimens were transferred to St. John’s lake, Cold 
Spring Harbor, in August, 1923, where their further progress 
may be noted. 
Ortmann remarks of the close relationship of cataracta and 
implicata, the latter differing from the former only by a thick- 
ening of the shell along its lower margin, a distinction hardly 
noticeable in young shells. Anodonta sp. are usually thin- 
shelled under any condition of environment. Their ready 
adaptation to the lime-free waters of Long Island is thus easily 
understood. EH. complanatus is a puzzling species due to the 
large number of variants representing it. While it is described 
as having a moderately thick shell, yet a form of it with shell 
so soft as to be easily indented with the finger, has been re- 
ported from a soft-water lake in New York (4). This would 
seem to indicate similar adaptability as the Anodontas. All 
are members of the depauperate Atlantic Coast Fauna, having 
been reported from New England by Johnson (5), and being 
found further south. The fair probability is their introduc- 
tion on Long Island, one way or another through the agency 
of birds. 
A similarly curious distribution is reported for A. cataracta 
from the Tennessee drainage. This shell is not found in the 
Upper Tennessee draniage above Chattanooga except at a 
