•524 Scientific Proceedings, Royal Dublin Society. 



described species, the specific name of which will remind the 

 student of the form of the infero-marginal plates : — 



It, nearly equal to 5 r ; breadth of arm at base equal to r. 

 Marginal plates about 30 ; the infero-marginals sharply cut off 

 at their free edge so as to be wedge-shaped and to leave a gap 

 between each plate. Spinulation of the supero-marginals nil, or 

 there are a few scattered spines, or prominent spines are pretty 

 regularly developed from the angle to the middle of the arm, one 

 on each plate, and more distally there are distinct spinous tubercles. 

 The arms taper rather rapidly, and near the tip the whole of the 

 dorsal surface is occupied by the supero-marginals. The adambu- 

 lacral plates are rather closely covered by fine spines, arranged in 

 two or more definite rows, or in two definite rows and the remainder 

 more irregular. About ten spines at the sides of the infero-mar- 

 ginals, some of which are so long as to extend beyond the hinder 

 edge of the plate next in front, and some of which are quite short. 

 Madreporite quite close to a supero -marginal. Colour in spirit, 

 straw to brown. 



Taken at 500 fms. off Black Rock, an islet off the mouth off 

 Blacksod Bay, Co. Mayo (St. 201.) 



R. r. 



52. 11. 5. 



51. 11. 



49. 11. 5. 



Psilaster andromeda, M. Tr. 



Forty-five miles off Blacksod Bay, Co. Mayo ; 500 fms. (St. 

 ^01). 



The specimen noted by Mr. Sladen {pp. cit. p. 688), has no re- 

 corded locality ; Mr. Gr. C. Bourne, while on H.M.S. " Research," 

 dredged a specimen from 400 fms. at 50" 29' 26'' N. ll'^ 4' W. 



It is to be pointed out that the " superambulacral plate," 

 which is a characteristic of Mr. Sladen's family, Astropectinidae, 

 is absent or at least non-apparent in well-grown examples of this 

 species. I do not feel called upon to arbitrate between the naturalist 

 just named and Prof. Perrier, who has placed this old species in his 

 own genus Goniopecten (see Miss. Sci. Cap Horn ; Echinodermes, 

 p. 189). 



