382 
EDWIN LINTON 
DISTRIBUTION 
This species was found only in Modiolus plicatulus. Their 
geographical distribution is somewhat irregular. It was soon 
noticed that mussels from some localities had none, while those 
from other localities yielded them in considerable numbers. Even 
two mussel beds which were near together might differ very 
markedly. For example, on August 10 I examined two lots of 
mussels from Ram Island on which I made the following notes : 
1. From the N.W. side near an old wreck, 36, measuring from 55 
to 75 mm. in length, most of them about 65 mm., above low tide 
in a kind of sedge, shells much corroded. No parasites found. 
2. From a point 50 yards south of the locality of the first lot, 
34, 35 to 75 mm., mostly about 55 mm., above low tide, sandy 
mud, about 75 parasites obtained. 
In general it may be said that mussels in confined coves do not 
have these parasites. The best localities for finding them are 
those which are exposed to rather free tidal currents. When they 
do occur in a bed of mussels they are rather more numerous in the 
large animals than they are in the small ones. 
Advantage has been taken during the process of publication of 
suggestions made by my friends Drs. Coe and Patterson, both of 
whom have shown a lively interest in this case of apparent poly- 
embryony. 
Dr. Coe writes me that he examined a lot of ribbed mussels 
from Savin Rock, New Haven, on Oct. 7, 1910, and finds the 
Graffilla fully as common as at Woods Hole. There was, more- 
over, an abundance of embryos in all stages in the larger 
specimens. 
