ASTEROIDEA 89 



next external plate. But the plates of central portion of abactinal surface are roundish, 

 and are not in contact. It is only the lateral-most part of the papular areas that have the 

 lobed plates, whereas in Bathybiaster all the papular area is provided with stellate, 

 imbricating plates. Furthermore, in Psilaster charcoti the non-papulated radial area 

 has very distinctly separated plates as in typical Psilaster. 



Bathybiaster loripes Sladen 



Bathybiaster loripes Sladen, 1889, p. 240, pi. 36, figs, i, 2; pi. 42, figs, i, 2. 



Goniopecten Fleuriaisi Perrier, 1891, p. 140, pi. 12, figs, za, 26; p. 190. 



Bathybiaster spimdatus Koehler, 1917, p. 55, pi. 6, figs. 13, 14, 16, 17. Kerguelen, shallow water. 



St. WS 98. Falkland Plateau, 49' 54' 15" S, 60° 35' 30" W, 171-173 m., 3 specimens. 



St. WS 216. Falkland Plateau, 47° 37' S, 60° 50' W, 219-133 m., fine sand, i specimen. 



St. WS 773. Falkland Plateau, 47° 28' S, 60° 51' W, 291 m., i specimen. 



St. WS 819B. Falkland Plateau, 52° 45' S, 62° 27^' W, 329-342 m., 8 specimens. 



A study of the extensive series of specimens of loripes and obesus indicates that obesus 

 is a circumpolar species, of which loripes is a northern, warmer water, race. It is un- 

 fortunate that the priority of loripes necessitates its use for the species in its widest sense. 

 It would be better biology to call the Falkland form Bathybiaster obesus loripes. 



The type of loripes from the western coast of South America, near the entrance to the 

 Strait of Magellan (245 fathoms) is only medium sized as compared with specimens 

 from the Falkland plateau, the largest of which has R no mm. 



Sladen 's figure depicts the spines as standing out from the rays, whereas in the 

 specimens under observation the inferomarginal spines are closely appressed and very 

 inconspicuous. This somewhat vivacious interpretation by the artist is of psychological 

 importance, since it may easily have influenced Koehler to believe that his B. liouvillei 

 (i.e. obesus) is more trenchantly different from loripes than really is the case. Some 

 specimens of loripes have inferomarginal spines as short as they are in obesus (Palmer 

 Archipelago), but the latter lack the superomarginal spines of loripes. These supero- 

 marginal spines of loripes are sometimes very inconspicuous. As an extreme variation, 

 they may be lacking ahogether, as in one example from St. WS 98 ; whereas two others 

 have small, broad, squamiform spines. 



Bathybiaster spimdatus Koehler, from shallow water, Kerguelen Island, was based 

 on only one specimen having R 90 mm., the description and figures of which leave 

 nothing to be desired. The spinulation of the marginal plates is the principal feature in 

 which spinulattis is believed to differ from loripes, its obviously nearest relative. It is 

 evident that Koehler relied solely upon Sladen's description and figures of loripes. In 

 his rather involved summary of differences, Koehler has invoked the shape, number, 

 and position of the marginal spinules, but his conclusions are untenable since specimens 

 of loripes may have as many spines as spinulatus, and in precisely the same position ! 

 For one item, the upper of the 2 or 3 inferomarginal spines is not always at the extreme 

 upper end of the plate, as Koehler believed, but in large specimens tends to drop a slight 

 but inconstant distance below, forming a somewhat irregular longiseries precisely as 



