56 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



Remarks. I have not been successful in discovering any constant characters 17 

 hv which Stimpson's cribraria can be separated from the curlier groenlandica of 

 I.iitken or the later spUziergensis of Danielssen and Koren. The last two species are 

 considered the same by Doderlein, 18 Grieg," and von Ilofsten (1915, p. 59). Verrill 

 at first united groenlandica and cribraria (1909, p. 553) but later (1914) kept them 



rate. In the latter work he compares cribraria with xpitzbergensis and concludes 

 thai thev are "identical hut variable." Professor Verrill's material was not abundant, 

 much of it consisting of depauperate and young specimens. With a large series at 

 his disposal I feel sure that he would have adhered to his first decision. 



Mortensen at first considered muUeri and groenlandica to he varieties of the same 

 species. He says: 20 "Though a typical A. groenlandica as to habitus differs very much 

 from a typical A. muUeri, especially of the var. islandica Levinscn, there is evidently 

 nut a single character to be relied upon by which they may be distinguished. I think 

 we must then conclude that thev can not be maintained as two distinct species. The 

 form groenlandica must be regarded as a more or less distinct variety of A. mulleri." 

 In his hitest publication, however, he definitely separates the two species. 21 



Von llofsten (1915, p. 59) adopts a middle course and classifies groenlandica as 

 an arctic subspecies of the boreal mulleri. 



Light is thrown upon the question by a comparison of breeding habits. Accord- 

 ing to Sars, 22 L. mulleri hroocls its young under the disk in a cavity formed b} r the 

 rays. In groenlandica the eggs and developing young are carried in the stomach. 

 It is inconceivable that the same species would develop two such fundamentally 

 different modes of caring for the young. 



L. arctica, the Bering Sea equivalent of midleri, is perfectly distinct in every way 

 from L. groenlandica. 



Leptasterias obtecta Verrill (1914, p. 144) is referable to groenlandica. I have 

 examined the type, No. 1208, Museum of Comparative Zoology, 12 miles east of 

 King's [sland, Bering Sea, 17 fathoms. The specimen is characterized by slender 

 spinelets very numerous crossed pedieellariae, and smaller than typical dorsolateral 

 papular areas. The skeleton of one ray was cleaned. It is not essentially different 

 from forma cribraria with the exception that on the proximal two-thirds of the ray 

 the transversely elongated papular areas adjacent to superomarginal plates are not so 

 broad as is usually the case in cribraria. Between the mesial ends of these meshes 

 and the irregular series of carina! plates are one or two irregular, very distinctly 

 smaller, papular areas. The supramarginal skeletal meshes are therefore larger than 

 the others and wider than long in most cases. The adambulacral plates of the 

 proximal half of ray are diplacanthid ; those of the distal half alternately monacanthid 

 and diplacanthid. The Henricia-like appearance of the dorsal surface is due to the 

 iiumerou ariai which on accounl of the slenderness of the abactinal 



lifJerence Is that of the adambulaa . , ,1 both forma cribraria and forma groenlandica 



of the Bering ,,| under Variations. In larpc Oreei land exam] les thi e , edicellariae are present, and they are 



sometimes very scanty In an 



; ' unt, newser., vol. *, Abt. Belgol. 1000. 



" K ' lltionin the" Fram" 1898-1902. ..nodermata, 1907, p 13 



inland, Med lei on . 



» Echlnoderms nftiie B 143, 



" Fnun " li,: Mortensen Echinoderms of the British Isles, 1927, p. 112. 



