390 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



only in the individuals from any given station, but even on the different rays of single 

 specimens. 



Each feature of the fully grown has its own developmental curve, but the correlation 

 between these different curves varies widely in different localities. Thus in the smaller 

 individuals, with an arm length of below 200 mm., this species occurs hi a wide variety 

 of more or less marked and intergrading forms, many of which are found with developed 

 sexual products. But as the larger individuals are all quite uniform, it is admissible 

 to assume that, no matter how extreme the differences in the correlation of the develop- 

 mental curves may be in specimens from different localities, these everywhere ulti- 

 mately reach the same, or approximately the same, correlation hi the fully grown. 

 In some places, however, as on the coast of New England and Nova Scotia, it appears 

 that a large size is never attained and the individuals never progress beyond an early 

 sexually mature stage which retains in varying degrees juvenile characters. Such a 

 condition also occurs in individuals found among masses of large and fully formed adults, 

 these being, possibly, the stunted victims of too crowded conditions. 



At the majority of the stations at which this species has been dredged, a few speci- 

 mens have been brought up together with various representatives of the other animal 

 groups ; but in certain restricted localities it has been found to be extraordinarily abun- 

 dant, often occurring hi enormous numbers almost to the complete exclusion of any of 

 the other marine animals. Thus Edward Forbes (in Forbes and Godwin-Austen, 1859) 

 wrote that, as he was informed by Prof. Goodsir, on the authority of a collector employed 

 by him to dredge at Spitzbergen, this species is so abundant hi water of moderate depth 

 that the bodies of the individuals frequently filled the dredge to the exclusion of all 

 other creatures. It has since been found to occur in similar abundance in isolated and 

 restricted localities throughout its range, excepting only within the region between 

 Cape Cod and Labrador. 



The localities at which it has been reported to occur in great numbers are 

 the following : 



Franklin Pierce Bay, Smith Sound; Murchison Sound, 46 meters; three miles off 

 Coutt's Inlet, Davis Strait, 237 meters; near Jan Mayen, 140-526 meters; east of Ice- 

 land, 630 meters; southeast of the Faroe Islands, 631-1156 meters; off Aalesund, Nor- 

 way, 820 meters; southwest and southeast of Bear Island, 130-200 meters, southwest 

 of South Cape, Spitzbergen, 145 meters; off South Cape, Spitzbergen, 114-146 meters; 

 west of Horn Sound, 115-160 meters; at Green Harbor, 140 meters; Spitzbergen 

 (?Advent Bay); at the entrance to Stor Fjord, 131.5-139 meters; near Cape Palander, 

 73 meters; and off Taimyr Land, 66 meters. 



The depth at these localities ranges from 46 to 1156 meters (234 meters less than 

 the range for all the localities from which the species is known), the average depth being 

 288 meters, which is very close to the average for all localities. 



The temperature varies between 1.60 C. and +2.30 C. (a range of 3.80 

 less than that for all localities), the average being 0.25 C., 0.46 less than the average 

 for all stations. 



At all of these localities the bottom was mud, or mud and stones, or gravel or 

 of a closely similar nature, which indicates that this animal thrives best on bottoms of 

 such a character and that the growth upon them of the large fixed and arborescent 

 plankton-feeding animals (Primnoa, etc.), which would compete with them for food, 

 is not possible. 



