EDITORIAL NOTE. 



This Volume contains the fourth and concluding Part of the Botanical 

 Series of Eeports on the Scientific Results of the Expedition, and 

 is a Memoir by Conte Abate Francesco Castracane degli Antelminelli 

 on the Marine Diatomace^e collected during the Expedition. The 

 Report was originally written in the Italian language, and was trans- 

 lated into English under the direct supervision of Conte Castracane ; it 

 has, however, been found necessary to submit this translation to consider- 

 able modifications of form before sending it to press. In some respects 

 it would have been desirable had the Author included in the Report 

 lists of the species found in the deposits and in the surface waters 

 of different regions of the ocean ; such lists will, however, be given in 

 the Report on Deep Sea Deposits. 



It was at one time hoped that an additional Report would be in- 

 cluded in this Volume upon Pelagic Alce other than the Diatomace^e, 

 such as Ocillatorise, Coccospheres, Rhabdospheres, and some other 

 organisms which are regarded as Pelagic Algse. The material brought 

 home was, however, not extensive enough, nor in a sufficiently good 

 state of preservation, to admit of the preparation of a satisfactory 

 Report ; indeed, it would not have been possible to add much to what 

 has been said about these doubtful organisms in the Narrative of the 

 Cruise, or to the remarks it will be necessary to make concerning them 

 in the Report on the Deep Sea Deposits. An interesting account of 

 these Pelagic Alg^ may be looked for from the first Naturalist, who 

 has the time and opportunity to examine [them in the living state on 

 board ship, immediately after having been taken from the waters of 

 the open ocean. 



John Murray. 



Challenger Expedition Office, 32 Queen Street, 

 Edinburgh, November 14, 1886. 



