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BULLETIN 16, UNITED STATES NATIONAL MUSEUM. 



species of Pteraster also, and are the normal means by which the large young escape 

 from the nidamental supradorsal cavity. The slits can not be regarded as a special 

 generic character. The young when they leave the parent are essentially like the 

 adult except in having more delicate membranes, fewer abactinal spines and spiracles. 

 The}'' are also exceptionally large, the largest one having a diameter of 20 mm. 



Tyfe. — Musee oc6anographique, Monaco (?). 



Type-locality. — Off Newfoundland, 155 meters. 



Distribution. — Bering Sea, from Bering vStraits south to Bering Island, Kam- 

 chatka, and Unalaska; Spitzbergen (Doderlein), Greenland (Mortensen), Newfound- 

 land (Perrier, Verrill). Evidently the species is circumpolar. The vertical dis- 

 tribution in Bering Sea is 17 to 85 fathoms; in the North Atlantic, 50 to 145 fathoms. 

 The specimens from Bering Island were evidently washed ashore as they are much 

 abraded. 



Specimens examined. — Twenty-seven, from the following locahties: 

 Specimens of Pteraster obscurus examined. 



6 Seven-rayed. <" Eight-rayed. 



Remarks. — Perhaps the first specimen of this species ever taken was that col- 

 lected by Dr. W. H. DaU near Bering Strait in 1874 (Cat. No. 6101, U.S.N.M.). 

 The species was not described until seventeen years later, and not recognized by 

 zoologists generally until after 1894 when Verrill described a specimen from off 

 Newfoundland Bank (lat. 43° 05' N.; long. 50° 43' W.). Perrier's preliminary 

 descriptions (1891) seem to have been overlooked, even by Perrier himself, for he did 

 not inclufle his new genus in the keys of the Travailleur and Talisman report, 1894. 



The work of the Albatross in Bering Sea, and the DaU specimen, greatly increase 

 the known range of this interesting form, which has hitherto been recorded only 

 from scattered localities in the North Atlantic. All the Atlantic specimens of 

 which I have seen any notices seem to be six- or seven-rayed, and smaller than the 

 largest Bering Sea example. There is Uttle doubt that the seven- and eight-rayed 

 specimens belong to the same species as the six-rayed. The structural details are 



