1048 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



only from the Gulf of Mexico or tbe Straits of Florida. Some belong to 

 genera that have always been considered as tropical or sub-tropical, such 

 as BoUum, Man/inella, ISoIarmm, and Avicula among the shells. In 

 fact this belt is occupied by a northern continuation of the southern 

 or West Indian Gulf Stream fauna. Our observatitms, both ®n the 

 animal life and the temperature, demonstrate that the western edge of 

 the Gulf Stream is much nearer this coast than it is located on most 

 modern charts. According to our experience the influence of the Gulf 

 Stream becomes decidedly marked, by the rise in tempwrature a few 

 fathoms below the surface, along a belt corresponding nearly with the 

 G5-fathom line, in summer. This is shown both by the abundant occur- 

 rence of the various pelagic animals, gulf-weed, «&c., characteristic of 

 the Gulf Stream water farther south, and by the temperatures taken by 

 us. The temperature curves, in 5, 10, 20, 30, and 50 fathoms, all illus- 

 tiate this, as well as the bottom temperatures. The English Admiralty 

 charts, and others, place the inner edge of the Gulf Stream in summer 

 entirely outside of the Slope, or 40 to 50 miles farther from the coast 

 than we found it. In summer, as is well known, the Gulf Stream is 

 noticed nearer the coast than in winter, but this doubtless applies 

 strictly, or chiefly, ohIj' to the surface water. But in summer, owing 

 to the heat of the sun, there is often very little difl'erence between the 

 temperature of the surface wattr at the Gulf Stream and on the inshore 

 plateau. Our investigations show that the warm belt, in G5 to 125 

 fathoms, is inhabited by a peculiar southern fauna that could not exist 

 there if the Gulf Stream did not flow along this area, at the bottom, 

 both in winter and summer. It is evident that what many of these spe- 

 cies require is not a very high, but a nearly ^iniform temperature^ all the 

 year round. Such an equable temperature could not exist in this region 

 except under the direct and constant influence of the Gulf Stream. On 

 the lower part of the Slope, in 300 to 780 fathoms, we found numerous 

 arctic forms of life, corresponding to the lower temperature, which at 

 300 to 500 fathoms is usually 41° F. to 40° F., and at 500 to 1,200 fath- 

 oms, 40° F. to 38® F. On the inshore plateau, which is occupied by a 

 branch of the cold, arctic current, about 30 miles wide, we found that 

 the temperature of the bottom water usually varied from 46° F. to 42° F., 

 in August, at the depths of 25 to 60 fathoms. In some instances it was 

 higher than this nearer the shore, and especially opposite the mouths 

 of the bays and sounds, where the tidal flow rapidly mingles the warm 

 surface water (70° F. to 75° F.) with the bottom water. 



On the cold part of the shore ])lateau we also found an abundance of 

 arctic species of animals, such as are found at similar and less depth 

 north of Cape Cod and in the Bay of Fundy. During the colder season 

 of the year the temperature of the water over this plateau is decidedly 

 lower, for codfish even are taken here in large numbers in winter. This 

 plateau, especiallj" over its shallower portions, has, therefore, a variable 

 cold climate. But the deep water below 300 fathoms has a tmiform 



