PELAGIC AND INTERMEDIATE DEPTHS FAUNA. 17 



Of the Dinoflagellates the following were recognized. 



Pj-roeystis Ceratium Ceratocoiys 



Exuviaella Gonyaulax Phalacroma 



Prorocentruni Goniodonia Dinnphysis 



(ileiKulinium Diplopsalis Ampliisolenia 



Ptycliodiscus Peridinium Omithocercus 



Pyropliacus Podnlampas Histoneis 



Steiniella Blepliarocysta Citharistes 



Protoceratiuiu Oxytoxuiu Cladopyxis 



The great changes of temperature which took place at some localities in 

 the layers of the water between 50 and 300 fathoms are most striking, and 

 show what a disturbing element the great mass of cold water flowing north 

 must be in the equatorial regions of the Panamic district to the south and 

 to the north of the Galapagos (Pis. o"; i, fig. ;>; 6, fig. 3; 10, fig. ,?). 

 South of the Galapagos the western flow of the Humboldt current must be 

 nearly 800 miles wide, and of about the same width when running parallel 

 to the South American coast. 



The range of temperatures between 30 fathoms and 150 fathoms is at 

 some points as great as 21" (PI. 4, fig. j). Such extremes cannot fail to 

 affect the distribution of the pelagic fauna, and may account for the mass of 

 dead material often collected in the intermediate tows at depths of less than 

 300 fathoms, when the range becomes as great as 28'. Such a range of 

 temperature is far greater than that of the isocrhymic lines which separate 

 coast faunal divisions. A preliminary examination of the contents of the 

 nets from 800 fathoms shows nothing which had not been obtained in lesser 

 depths of from 300 to 150 fathoms from the surface. These nets coming 

 from 800 fathoms, as at Station 4517,* contained a mass of dead and mori- 

 bund material collected on its way to the bottom. A lot of Copepods came 

 up, fully 65 per cent of which were dead. Of the Dinoflagellata, most of 

 them had no chlorophyll, and of the Radiolarians many were the skeletons 

 of surface colonial forms. At Station 4697 at 300 fathoms to the surface 

 more than one-third of the contents of the net was dead. 



At 800 fathoms at Station 4701, of the Copepods in the net, 25 per cent 

 were dead, and of the Radiolarians, 70 per cent. 



From 800 fathoms at Station 4715, a great deal of dead material and 

 debris was collected, mainly of Diatoms and Dinoflagellates. 



From the same depth, at Station 4717, many dead Globigerinoe were 

 obtained, and 25 to 30 per cent of the Copepods collected were dead. 



