41 10 . Proceedings of the Royal Irish Academy. 



all times creatures of the open shallow seas, and ai'e rarely found in harbour 

 and bays unless driven there under stress of weather. 



The following species of Mysidae may be regarded as purely littoral 

 species : — 



Siriella armata. Macropsis slabberi. 



S. jaltensis. Maeromysis flexuosa. 



S. clausii. Schistomysis arenosa. 



Heteromysis formosa. Neomysis integer. 



Leptomysis lingvura. 



The species of Gastrosaccus and Anchialus are more purely pelagic than 

 the other Mysidae, but only G. norrnani extends seawards for any distance. 

 It has been recorded from a depth of 180 fathoms. 



The remaining species are bottom-living forms which range from all 

 depths down to about fifty fathoms. 



