62 



ECHINODERMS OF THE BRITISH ISLES 



In the British seas this species has been found in the Faroe 

 Channel, the cold area, 344 m. (" Porcupine ") ; further at 

 50° 22' N., 11° 44' W., 1797 m., and 57° 41' N., 11° 48' W., 

 1853 m. (" Michael Sars "). It appears to be distributed all over 

 the North Atlantic, both on the European and American side, 

 up to Umanak Fjord on the west coast of Greenland. Further, 

 it appears to occur all over the Norwegian sea (the cold area), 

 from the Faroe Channel to Spitz bergen and east Greenland. 

 Known bathymetrical distribution, 223-2222 m. 



It has been maintained recently (Grieg) that the form occur- 



Fia. 35. — Bathyhiaster vexillifer, oral and aboral side. Somewhat reduced 



in size. 



ring in the cold area, the true B. vexillifer, is to be distinguished 

 as separate from the form of the warm area, B. robustus Verrill. 

 Besides a slight, not quite constant difference in the number of 

 spines on the marginal plates, and a somewhat more vertical 

 position of the marginal plates of the basal part of the rays in 

 B. robustus, the only real difference is stated to be this, that the 

 skeletal plates of the dorsal side are stellate, over-lapping, in the 

 cold-water form, round or polygonal, not over-lapping, in the 

 warm-water form. This character, liowever, the present author 

 finds to be also inconstant, and thus there is not a single 

 reliable character by which to distinguish the two forms. At 



