156 



the distribution of temperature, &c., and of the conditions suitable to the 

 existence of animal life at great depths in the ocean. 



After leaving Cork the vessel stood out two himdred miles to the south- 

 west of Ushant, with admiralty soundings marked at two thousand 

 fathoms. At a depth of two thousand four hundred and thirty-five fath- 

 oms Atlantic chalk mud was met with, and a temperature of 36.5° 

 Fahrenheit noted. At another dredge, at a depth of tw^o thousand 

 fathoms, the temperature was SGA^. 



The results obtained are among the most interesting that have been 

 made in natural science. In reference to temperature Professor Thomson 

 says: 



The superheating of the sun extends only to the depth of about twenty fathoms. 

 Another cause of superheating, probably the Gulf Stream, extends to the depth of from 

 five hundred to seven hundred fathoms ; after that the temperature gradually sinks at 

 the rate of 0.2° (two-tenths of a degree) for every two hundred fathoms. This is, 

 probably, the normal rate of decrease, any deviation being produced by some special 

 cause, a warm or cold current. 



In regard to the aeration of the water, Mr. Hunter, who accompanied 

 Professor Thomson, states that he found the water from great depths to 

 contain a large excess of carbonic acid, and that the water from all depths 

 contained a considerable proportion of dissolved organic matter, thus in 

 every way bearing out the observations of Mr. Carpenter during the first 

 cruise for this object. 



As to the distribution of animal life he remarks : 



Life extends to the greatest depths, and is represented by all the marine invertebrate 

 groups. At two thousand four hundred and thirty-five fathoms we got a handsome 

 deniaUum, one or two crustaceans, several annelids and zephyrea, a very remarkable new 

 criuoid with a stem four inches long, (I am not prepared to say whether a mature 

 formed or a pentacnnoid,) several star fishes, two hydroid zoophytes, and many foramini- 

 fera; still the fauna has a dwarfed and Arctic look. This is, doubtless, from the cold, 

 At eight hundred to nine luindred fathoms, with a temperature pf 40^ Fahrenheit and 

 upward, the fauna is rich, and specially characterized by the great abundance of 

 vitreous sponges, which seem to be nearly related to, if not identical with, the ventriculites 

 of the chalk. 



The result of the year's work has been to bring to light many forms new to science, 

 and many new to the British /auna. Among the most remarkable groups I have been 

 working at I may mention a very singular echiiioderm, representing a totally new group 

 of the sub-kingdom, a splendid new ophiurid, many specimens of Sars' rhizocrinos loffo- 

 fe»8i«, many vitreous sponges, including specimens of aphrocalliste8,hoUcnie8, and hyalo- 

 mena, a fine solarium from the coast of Kerry, and many other things. 



The results of Professor Thomson's researches entirely upset the long- 

 maintained opinion that animal life was impossible at great depths in 

 the ocean. 



Floating Tunicates of the Atlantic. — In an interesting paper 

 on the tunicated animals of the Atlantic of the order salpidce, Mr. Cuth- 

 bert Collingwood describes some beautiful appearances to be observed as 

 follows : 



On one occasion when the sea was dead calm, and I was watching the floating tuni- 

 cates, aud fly drozos, though the ship scarcely moved, my attention was arrested by a 

 magnificent object hovering at some distance below the surface. It had the appearance 

 of a long, convoluted, and delicate chain of gems, of the most brilliant colors, which 

 waved gracefully in the currents of water. It might be compared to a necklace of 

 diamonds, set in rubies, and although not the organism to which the name of cestus 

 veneris has been given, it might have been the jewelled girdle of Venus falling from her 

 as she rose from the sea. Not far from it was another oljject, if possible, even of greater 

 beauty, consisting of five or six dolpiform bodies, arranged in oblique line, each of a 

 bright and delicate emerald green color as clear as crystal, and possessing a large red 

 ruby spot, which shone in the water like a row of magnifient carbuncles. There can 

 be no donbt that these exquisite objects were chains of salpoe., of a character unknown 

 to the scientific naturalist, though they may have often charmed the eyes of the be- 

 calmed sailor, and they illustrate the unknown riches and infinite variety of the crea- 

 tures which lie concealed in the impenetrable depths of the inscrutable ocean. 



