536 Mr. J. Murray on some Surface Organisms examined 



Many other Rhizopods, with more or less flask-shaped or bivalved 

 siliceous shells, which are undescribed, so far as is known. 



Mr. Wild has figured six of these last in Plate 24 ; for the sake of 

 convenience we have been accustomed to call the organisms Challengeridae. 

 This provisional name will be retained if it be found that these organisms 

 are new to science and universally distributed in deep water. 



The shells of all have an exceedingly beautiful tracery, a fenestrated 

 appearance often, which was at first supposed to be due to perforations 

 of the shell, but which a closer examination shows to be caused by pit- 

 like depressions. Some have only one, others have several openings 

 through which the sarcode flows. The sarcode of all these deep-sea 

 Rhizopods has many large black-brown pigment-cells. Small bioplasts 

 are scattered through the sarcode. These collect into capsular-like 

 clumps when the animal is at rest, and are quickly coloured by carmine. 

 At times these Challenged dae come up with a good deal of the sarcode 

 outside of the shell; and two specimens have been seen to throw out 

 elongated pseudopodia. 



I should think that not less than fifty species of these organisms have 

 been taken in the deep nets already. They all resemble more or less 

 those forms drawn by Mr. Wild. It will be interesting to learn if future 

 investigations will show these organisms to be present in the deep waters 

 of the Atlantic as well as the Pacific. In the Eadiolarian oozes the 

 remains of these ChallengeridsD make up a considerable portion of the 

 deposit, and in some other deposits of the North-west Pacific they are 

 well preserved. In the majority of bottoms, however, they appear to be 

 quite absent. 



Pteropods, Heteropods, Pelagic Gasteropoda. — Species of these orders 

 occur everywhere in the surface-waters of the ocean. Their shells make 

 up a large portion of some deposits in shallow water, where there is 

 relatively little land-debris. 



In depths less than 1500 fathoms they abound ; deeper than this they 

 become more and more rare. At 2000 fathoms and deeper the only 

 trace of these shells in the deposits is an occasional Diacria or Iantliina 

 of a large size. 



Those shells which are thin and delicate, as Atlanta, Carinaria, "and 

 Styliola, disappear first from the bottoms. 



Geneeal Eemarks. 



Everywhere we have found life abundant in the surface and subsurface 

 waters of the ocean. If living creatures are small in number on the 

 surface, the tow-net will usually yield many forms if dragged at a depth 

 of 100 fathoms or more. We have not met with any really barren 

 regions. Our observations appear to show that there are several regions 

 of the surface of the ocean, each of which is characterized by a number 

 of peculiar organisms : — 



