A NEW HYDROID FROM LONG ISLAND SOUND. 
CHAS. P. SIGERFOOS. 
Durine the summer of 1898, while enjoying the facilities of 
the seaside laboratory of the Brooklyn Institute of Arts and 
Sciences at Coldspring Harbor, Long Island, the writer found 
a hydroid which possesses special interest on account of the 
peculiar features which characterize it. The specimens col- 
lected last year were obtained ona single day, and a description 
has been delayed that new data might be added through wider 
observations during the present summer. 
Early in August, 1898, while exploring the east end of 
Lloyd’s Harbor, a part of Huntington Bay, small flocculent 
masses of different colors were observed in considerable num- 
bers on the eelgrass which forms a dense growth on the bottom. 
Again this year the same locality was visited several times 
from July 8 to August 16, and each time numerous specimens 
were collected. The small cove in which they were found is 
a few acres in extent and well sheltered from high winds, so 
that the surface is usually smooth. During high tide the water 
may be ten feet deep, but at low tide the grass forms more or 
less of a mat upon the bottom. 
Casually examined, the flocculent masses appeared quite 
similar to the well-known hydroid Hydractinia, found abun- 
dantly on our Atlantic coast, including Long Island Sound. But 
examined more carefully, it was found that the inhabitants of 
the shells on which the hydroid lives are living snails (//yanassa 
obsoleta), and not the hermit crabs with which Hydractinia is 
most frequently associated. Also, that the make-up of the 
colony as a whole and the character of the individuals are 
different from those of Hydractinia. 
A general view of a female colony, natural size, is shown in 
Fig. 1, in which the snail is represented as moving slowly over 
a blade of eelgrass. Though the colonies are rather small, the 
Sor 
