218 THE VOYAGE OF H.M.S. CHALLENGER. 



detect with its imperfect organ of vision. Several species were discovered in the South 

 Pacific as well as the South Atlantic, at depths varying from 520 to 2650 fathoms." 



When taken from the trawl these fishes were always dead, and the long pectoral rays 

 were erected like an arch over the head, requiring considerable pressure to make them lie 

 along the side of the body ; when erected they resembled Pennatulids like Umbellula. 



On the voyage from the Cape Verde Islands to Bahia the tow-net was worked with 

 greater regularity and more successfully than during the early part of the cruise. The 

 method of lowering and towing it at depths of 50 and 100 fathoms beneath the surface 

 while the ship was dredging and sounding was adopted, and. proved a great success. In 

 this way many animals were taken during the day which had previously only been 

 captured on the surface at night. 



Except during calm weather, very few animals were found near tbe surface in the 

 day time. Mr Murray's researches led him to conclude that the great majority of 

 pelagic organisms live at various depths down to, and even deeper than, 100 fathoms 

 during the day time and rough weather, and only come to the surface during the 

 night and in calm weather. In this trip along the course of the Guinea and Equatorial 

 Currents pelagic life was much more abundant and varied, both in individuals and 

 species, than anywhere else in the North or South Atlantic. 



The occurrence of the following organisms was noted during the trip. The greatest pro- 

 fusion of life was observed in the Guinea Current during calms, when the sea literally teemed 

 with life, and the most magnificent displays of phosphorescent light occurred at night. 



Trichodesmiwn, and other Oscillatoriae. 



Large specimens of Coscinodiscus and other Diatoms, free and attached to 



Copepods and other organisms. 

 Ehabdospheres, Coccospheres. 

 Pyrocystis noctiluca and Pyrocystis fusiformis. 

 Amoeba and amoeboid particles. 



Peridiniurn tripos (single and in catena), and other species. 

 Vorticella, Acineta, Podophrya (on Pteropod shells), and other Infusoria. 

 Many Radiolaria (compound and simple). 

 Pulvinulina, Sphceroidina, Globigerina, Hastigerina, Orbulina. Candeina, and 



Pullenia. 

 Hydromedusoid stocks (on Pteropod shells). 

 Hydromedusse. 



Physalia, Diphyes, Velella, Porpita, and many other Siphonophora. 

 Semper's Ccelenterate larva. 1 

 Scyphomedusse. 



1 Zeitschr. f. wiss. Zool., Bd. xvii. pp. 407-411, 1867. 



