34 Prof. W. Thomson on the [Nov. 18, 



and a large number of Echinoderms, chiefly flexible sea-urchins, ophiurids, 

 and starfishes of the genus Brisinga. The hydroid zoophytes were repre- 

 sented by a very remarkable species, apparently referable to the genus 

 Monocaulon of Sars, a Corymorpha-like solitary polyp with adelocodonic 

 gonophores ; but instead of being of the proportions usual in its group, 

 the stem in one of our specimens measured upwards of seven feet in height, 

 while the polyp-head was nine inches in diameter across the proximal row 

 of tentacles. "We afterwards got another fine example of the same species 

 at a depth of 2900 fathoms (Station 248). The temperature of the surface 

 of the sea stood during the day at nearly 23° C, considerably above the 

 temperature of the air; and a serial sounding gave the isotherm of 10° C. at 

 a depth of little more than 200 fathoms. We were therefore evidently under 

 the thermic influence of the Japan current, which was found by observa- 

 tion to be running in an easterly direction at a rate of 1| knot an hour. 

 The thermometers registered a uniform temperature of l°-7 C. from a 

 depth of 1000 fathoms to the bottom. About twenty Albatrosses, of a 

 nearly uniform brown plumage with whitish heads (probably the young of 

 the common North-Pacific species in their second year's plumage), followed 

 the ship. 



On the following day there was a stiff breeze from the southward, 

 with a heavy sea. "We sounded, however, successfully in 3950 fathoms, 

 our deepest sounding in the North Pacific — position by dead reckoning lat. 

 34° 43' N., long. 144° 2' E., with a bottom of " red clay." The gale con- 

 tinued on the 19th, and the weather prevented our attempting to trawl ; 

 but a sounding in 3625 fathoms and serial temperatures to 1500 fathoms 

 were obtained. At both of the two latter stations the high surface-tem- 

 perature was maintained ; and the position of the isotherm of 10° 0. at 

 station 239, at a depth of nearly 300 fathoms, indicates that up to this 

 point, at all events, there was no diminution in the influence of the " Kuro- 

 Siwo." 



On the 21st we sounded in 2900 fathoms, with a bottom of " red clay." 

 An attempt was made to trawl ; but the sea was still running high, and 

 in hauling in the line parted. 



The temperature-observations gave a singular result. The surface- 

 temperature had fallen to 18°-2 C, and the belt of water above 10° C. was 

 reduced in depth to considerably less than 100 fathoms, while all the iso- 

 therms, at all events to a depth of 400 fathoms, rose in proportion. 

 There seems to be little doubt, from a comparison of the American tem- 

 perature-results with our own, that this sudden diminution of tempera- 

 ture is due to a cold surface-flow from the sea of Okhotsk, probably 

 through Pico Channel or Vries Strait. Very likely its effect may not be 

 found to be constant ; and at this season it possibly attains its maximum 

 from the melting of the snow over the vast region drained by the Amoor 

 and the Udi and Siberian rivers with a southern outflow. 



June 23. — We sounded in 2300 fathoms, with a bottom of " red clay." 



