248 



conformity with the well known fact that most pelagic animals avoid 

 the strong dayhght by going down in the sea, raising again to the 

 surface at night time. I would expect that samples taken by night will 

 prove larvse to occur also all over the Arabian Sea. But that remains to 

 be proved. 



Besides the material of plankton samples collected for me on various 

 cruises across the Atlantic by Messrs. Blegvad.Kramp and Fogh (comp. 

 p. 10) I have also had the opportunity of examining some other samples like- 

 wise taken on the way to and from the West Indies, kindly placed at my dis- 

 posal by Dr. Johs. Schmidt. The samples were all taken at the surface 

 by night time. The following larvse were obtained from these samples. 



Sphserechiniis granularis . . . 36°13' N. 



— — . . . 36°42' 

 Echinopluteiis iransversus . . 32°10' 



— — . . 27°10' 

 — . . 34°22' 



— - . . 28°43' 

 Echinopluteiis sp 25°40' 



— 18°45' 



Luidia ciliaris 36°13' 



— — 37°31' 



— SarsiC!)^) 30°30' 



Bipinnaria sp 40°47' 



— 32°22' 



— 20°46' 



— 19°36' 



— 23°15' 



— 25°16' 



— 24°33' 



Auricularia nudibranchiala . 30°30' 



— — 33°55' 



— — 34°39' 



— — . 36°13' 



— — 39°22' 



— — . 40°47' 



— — . 45°32' 



The result is seen to be in fair accordance with that previously obtained 

 from the study of the material collected by the Plankton-Expedition, viz. 

 that, while in general the Echinoderm larvse occur more numerously in the 

 coastal waters, several specimens may be found also in mid-Ocean. This 

 raises the interesting problem: how did they come there? Were they carried 

 out from the coastal waters by the currents, or did they rise from the 

 bottom? 



So long as we do not know the parental origin of the larvse found in the 

 open sea the question cannot be answered definitely. Most probably they 



1) Identification of the single specimen a little uncertain on account ot the very poor 

 preservation. •' '^ 



