DESCRIPTIONS OF NEW SPECIES OF RECENT UNSTALKED 

 CRINOIDS FROM THE NORTH PACIFIC OCEAN. 



By Austin Hobart Clark, 



Of the United States Bureau of Fisheries. 



T\iif< paper is based upon material collected by the United States 

 Fisheries steamer A/I)afross in the Pacilic Ocean north of Mexico and 

 southern Japan. All but two of the species were collected on the 

 recent Japanese cruise in the Bering' Sea and about Japan, The 

 Eschrlcht'ii group is best represented in regard to numbers, with over 

 1,750 specimens, mostly of Bering Sea and eastern Pacific forms. 

 Unfortunately, Antedon eschriehtii var. maxima is so large (about 3 

 feet in diameter) that on the last cruise, although we obtained it in 

 enormous numbers — on one or two occasions, in fact, there was very 

 little else in the trawl — we found it impracticable to preserve an 

 extensive series. The species of this group in the eastern Okhotsk 

 Sea, off eastern Japan, off the Pacific- American coast, and in the Bering 

 Sea are all remarkable for the strong overlapping of the arm joints, 

 which have serrate distal edges, a fact which was first noticed for this 

 district by Hartlaub in Antedon tanneri from Panama. The lower 

 pinnules also have a distal comb, resembling that in some species of 

 Coniatida, but much longer than is usual in that genus. Another 

 interesting fact is that the species from the western American coast 

 all have the third syzygy in the fourteenth brachial and not in the 

 twelfth, as do those from the Bering Sea and Asiatic coast. The dis- 

 tal intersyzygial interval in the North Pacific species (excepting' those 

 from southern fbipan and the Japanese Sea) is almost invariably two 

 joints, whereas in most of the others it is three. All these species 

 will be more fully described and figured in my report on the North 

 Pacific crinoids. 



The following keys have been prepared with reference to all of the 

 described species in the respective groups, and it is believed that the 

 information given in them is amply sufficient to differentiate the new 

 species from any of those given in the Challenger reports or subse- 

 quently described. 



Proceedings U. S. National Museum, Vol. XXXlll— No. 1559. 



69 



