188 THE OCEAN 



and the Dalliidae by the Galaxiidae. Lycodes 

 is represented in the southern as well as in 

 the northern hemisphere, and Giinther thinks 

 that the re-appearance of so specialised a genus 

 in the Antarctic is remarkable. Stomias boa 

 and Halosauropsis macrochir are apparently 

 bipolar forms. 



Tunicates. — ^H. Lohmann remarks on the 

 striking relationship between Arctic and Ant- 

 arctic forms of Appendicularians as compared 

 with the relationship between polar forms and 

 those of the tropics. At both poles there are 

 closely related species of the genus Oikopleura 

 and one identical species of the genus 

 Fritillaria (F. horealis). 



Echinoderms. — Hjalmar Theel writes that 

 the shallow-water Holothurioidea of the far 

 north and far south possess much the same 

 features, and the distinguishing characters are 

 often inconsiderable and possibly not of specific 

 value. Elpidia glacialis, common in the North 

 Atlantic and Arctic Oceans, was taken by the 

 " Challenger " south of Australia. Euphron- 

 ides depressa is also bipolar, and Edmond 

 Perrier says that Psolus squamatus is present 

 both in the northern and in the southern 

 regions, while Clement Vaney says the Ant- 

 arctic species (Psolus segregatus) is quite 

 distinct. Alexander Agassiz was unable to 

 distinguish the specimens of Echinocardium 



