190 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [494] 
RADIATA, 
Hydroids. 
Page. | Page. 
Obelia gelatinosa....-.---- 482 , Halecium gracile.......--- “328 
O. pyriformis ..--..+------ 390 | Parypba crocea ..-..--.-.- 482 
O. diaphana ...--....--+-- 27 | 
Polyps. 
Page. Page. 
Sagartia leucolena.....-..- 329 ° Metridium marginatum.... 329 
IV.—FAUNA OF THE OCEAN SNORES AND OUTER COLD WATERS. 
All along this cvast, from Cape Cod to Stonington, Connecticut, there 
isa belt or current of cold water which impinges directly against the 
outer islands and the open coast, especially where there are points of 
land projecting outward toward the deeper waters. This is especially 
noticeable at Gay Head, on Martha’s Vineyard, No Man’s Land, Cutty- 
bunk Island, Montauk Point, Block Island, Point Judith, and Watch 
Hill. This cold water is undoubtedly derived from the Arctic current, 
which passes slowly southward in deep water off our coast, but whether 
an actual current, distinguishable from the tidal currents, exists in the 
waters of moderate depth along the coast is still uncertain. The tidal 
currents apparently have the effect of bringing the cold water of the 
outside regions up into the shallower localities along the shores, and it 
is probable that the presence of the cold water in moderate depths is 
due to the joint action of the tides and the slow-moving Arctic current, 
which impinges more or less against and upon the slope of the sub- 
merged eastern border of the continent. But the position, extent, and 
temperature of this cold water along our shores varies greatly, accord- 
ing to the direction of the tidal currents and the surface currents 
caused by the wind. We have shown, on a former page, that at times 
these local winds and tidal currents are able even to bring Gulf Stream 
water and its characteristic animals directly upon this coast, evenas far 
westward. as Watch Hill, Rhode Island, where the Physalia is often cast 
ashore insummer. At such times the cold current must necessarily be 
wholly displaced, or disguised by intermixture with the warmer waters. 
When the tide is flowing from Long Island Sound, Vineyard Sound, or 
other large bodies of warm water, the cold waters will also be displaced 
and the temperature raised even at the distance of twenty or thirty miles 
from the shore in summer. In winter there is comparatively little 
effect from the Gulf Stream, owing to the prevalence of northerly winds, 
and there is also far less effect from the warm waters of the sballow 
bays and sounds carried by the tides. Therefore the full effect of the 
northern current is felt only in winter, and it doubtless adds to the cold 
proper to the season and land climate. 
In winter and early spring we accordingly find numerous species ot 
northern animals and alge which disappear partially or wholly in many 
