REPORT ON THE ASTEROIDEA. 



183 



From Mr. Smith's account we learn that the same form had been collected at Ker- 

 guelen by the Antarctic Expedition of 1840, but that the species had remained unnoticed 

 and undescribed until worked out by him. Several specimens were obtained by the 

 Challenger Expedition from the same locality. 



I have referred to this genus the North-Atlantic form described by Sars under the 

 name of Astropecten arcticus, which has since been erroneously relegated to the genus 

 Archaster. 



Chorology of the Genus Leptopty chaster. 



a. Geographical distribution : — 



Atlantic : One species between the parallels of 35° and 75° N. 



Leptopty chaster arcticus off the North Cape, the coast of Norway, 

 and off the eastern coast of North America. 

 Southern Ocean : Two species between the parallels of 40° and 50° S. 



Leptoptychaster Tcerguelenensis off Kerguelen Island and Marion 

 Island. Leptoptychaster antarcticus between Marion Island and Ker- 

 guelen Island. 



O 



/3. Bathymetrical range: 10 fathoms to 1350 fathoms. 



Greatest range of one species : Leptoptychaster arcticus, 20 fathoms to 690 

 fathoms ; and the American variety of the same species, Leptoptychaster arc- 

 ticus, var. elongata, extends to 1350 fathoms. 



y. Nature of the Sea-bottom: Leptoptychaster arcticus is found, at least in the Euro- 

 pean area, on clay, sometimes sandy. The American variety, Leptoptychaster 

 arcticus, var. elongata, occurs on gravel and stones, and an example from 1350 

 fathoms on blue mud. Leptoptychaster antarcticus, on hard ground (gravel, 

 shells). Leptoptychaster Tcerguelenensis on volcanic mud, 



CTiorological Synopsis of the Species. 



1 This depth is recorded by Sir Wyville Thomson for Leptoptychaster arcticus, west of Ushant (Depths of 

 the Sea), but I have not seen a specimen. Verrill states that this species was dredged by the " Albatross " in 

 1883 in 547 fathoms (Report of Commissioner of Fish and Fisheries for 1883, Washington, 1885, p. 542). 



