ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS— FISHER 



69 



I had already set aside PediceUaster sexradiatus Perrier and P. improvisus Ludwig 

 as a generic group quite distinct from PediceUaster, when the similarity of the first 

 species to Hydrasterias opUdion Sladen occurred to me. At my request Dr. R. 

 Kirkpatrick, of the British Museum (to whom I have been indebted repeatedly for 

 information' concerning types then under his care), examined the oral region of the 

 unique specimen of Hydrasterias ophidion, made excellent photographs and sent a 

 small piece of the dorsolateral integument with numerous pedicellariae. 



Doctor Kirkpatrick's observations and photographs prove, as I suspected, that 

 the first pair of postoral adambulacral plates are widely separated as in PediceUaster. 

 Indeed the alliance of Hydrasterias with PediceUaster might be inferred from Sladen s 

 figure showing clearly the biserial tube-feet and wide-meshed delicate skeleton 

 But it could not be satisfactorily established without knowledge of the structure of 



the oral angle. . , , 



The relationship of Hydrasterias ophidion to H. sexradiata remams to be worked 

 out They are probably races of the same species, or may be the same species. 

 Specimens of H. sexradiata from latitude 37° north, longitude 27° west, 1,600 me- 

 ters however have good sized spatulate, denticulate straight pediceUanae in the 

 inte'rradial region. The crossed pedicellariae of sexradiata are closely similar to those 

 of ophidion which are figured herewith. (PI. 27, fig. 8.) 



Hydrasterias improvisa (Ludwig) 24 was dredged by the Albatross at stations 

 3362 3400 and 3407, east of Cocos Island and near the Galapagos Islands, in 1,175, 

 1 322 and' 885 fathoms. It is a five-rayed form with quite distinct crossed pedi- 

 cellariae, which, however, are of the same type as those of ophidion. (PI. 27, fig. 7.) 

 Clark's 25 record of improvisa from station 5675, 284 fathoms, southwest of 

 San Cristobal Bay, Lower California, is based upon a specimen which is described in 

 this work as Anteliaster coscinactis megatretus. 



Genus ANTELIASTER Fisher 

 Anteliaster Fisher, Ann. and Mag. Nat. Hist., ser. 9, vol. 12, 1923, p. 252. Type A. coscin- 

 actis Fisher. 

 Duwnosis —Differing from PediceUaster in the arrangement of the aetinal plates 

 which are in one to three normal longitudinal series (not in transverse series with 

 more numerous plates to a series distally than proximally), and in lacking promment 

 terminal claws on the jaws of the crossed pedicellariae; adambulacral armature a 

 transverse comb of two to five slender spinelets, conspicuously longer than any of the 

 others, except the oral spinelets (which form a longitudinal senes on each plate); 

 large, spatulate, sometimes unguiculate straight pedicellariae may be present. 

 Gonads opening ventrally. 



KET TO KNOWN SPECIES Or ANTELIASTER 



a'. Abactinal papulae on rays; mouth plates larger dorsolateral ami 



fc> Laree hand-shaped unguiculate, straight pedicellariae; skeleton with three dorsolateral ana 



'two fctinal .eries of meshes; spinelets with numerous terminal thornlets coscmadis Fisher 



P.XXSSt Scellariae; sUelLn very open with two dorsolateral -dthr^^ 



meshes; spinelets with three or four terminal thorn mcgatnlu, 



-"^^l^or^^ol. 32, 1905. r » BuU. Amer. Mus. Nat. Hist., vol^U.13. p. 202. 



