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NEW LIGHT ON THE BIOLOGY OF SPIRULA, 

 A MESOPELAGIC CEPHALOPOD 



By 



Anton Fr. Bruun 

 The Galathea Expedition 1950-52, Copenhagen 



1. INTRODUCTION 



In many parts of the world, especially in the tropics, the beautiful 

 white shells of the small cephalopod, Spirula, may be found cast ashore. 

 Often they are the most abundant species amongst the shells, and if the 

 sediment were fossilized, the Spirula shells would form the most char- 

 acteristic fossil. These accumulations represent mixtures of oceanic and 

 littoral species, which will constitute a puzzle to the future geologist. 

 I do not intend to discuss similar puzzles of the past, but shall confine 

 myself to the problems concerning Spirula. The discrepancy between the 

 countless numbers of shells found, even in high latitudes (e.g., Morch, 

 1868), and the few living specimens caught, to this day, induces one to 

 extract all possible information from any new catch. 



Until the time of the Danish Dana-Expeditions of 1920-22, only 13 

 living specimens had been captured. The leader of these expeditions, 

 Johannes Schmidt (1922), gave his observations on live specimens, as 

 well as a short outline of results derived from the study of the 95 speci- 

 mens caught on the expeditions. Ninety-three more specimens were added 

 during the Dana's circumnavigation of the globe in 1928-30, on which 



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