36 l l LLETIN 76, UNITED STATES NATIONAL MUSEUM 



Pcxcription.- The surface of the body has the appearance of being covered with 

 close-sel Blender, subterete, uniform, small spinelets emerging, in alcoholic speci- 

 mena, from a pulpj sheath, carrying in the small specimens usually few crossed pedi- 

 cellariae, The spines are pretty uniformly spaced, but vary considerably in number. 

 In small, T examples (as with K 25 to 30 inui.) from station 2847 the spinelets appear 



ru;ii>e dap, with very carrot interspaces between the sheaths of neighboring 

 spinelets; in others there are much wider interspaces with an evident arrangement of 

 spinelets in longiseries, although sometimes with no great regularity. The abactinal 

 spinelets are typically very much slenderer than in arctica, terete, slightly tapering, 

 terminally striated in large examples and bluntly pointed. In typical, small, deep- 

 water examples (as stations 2845, 2846, 2847, 2851, 2856) this character is accentu- 

 ated, the spinelets being very delicate and sometimes almost setalike — quite different 

 from the stout capitate spinelets of arctica. But in some localities the spinelets are 

 heavier, slightly clavate, with a rounded striated summit (as stations 4281, 3260, 

 3261, 3265). In liylodes there is no crowding of the carina! spines, nor are they dis- 

 tinguishable by greater size from the others, except in a few aberrant specimens, 

 where the discrepancy is slight. One of the most characteristic features of this 

 species is the uniform appearance of the abactinal area — entirely unlike that of 

 typical arctica. 'Phis is as well marked in the relatively gigantic type (and in an 

 equal si/.ed specimen from station 2847) as it is in the general run of specimens which 

 are small, though sexually mature (as station 2856). In the type the dorsal spines 

 are 0.90 to 1.2 mm. long. 



The supero and infero marginal spines form two usually very regular lateral 

 is, and in all but the smallest specimens there is an incomplete series of actinals, 

 the number varying from a few spines to a nearly complete series. There are thus 

 three ventrolateral rows of spines, which in typical specimens are similar to the 

 dorsals, though usually larger, and in the case of the inferomarginals and actinals 

 slightly heavier in small examples and markedly so in large ones. There is great 

 variability in the thickness of these marginal and actinal spines, just as there is in 

 the dorsal. A short series of smaller interinarginal spinelets is generally present. 

 The superomarginals have a complete wreath of pedicellariae, the inferomarginals 

 a complete or an incomplete wreath and the actinals a tuft on the outer side, the 

 number of pedicellariae variable but not high. The marginal and actinal spines in 

 the largest examples are less regular than in the small. 



AdambulacraJ spines slender, subterete, slightly tapered, bluntly pointed, one 

 or two to a plate in fairly regular alternation, except on the first dozen plates which 

 may earn mostly one, or mostly two, spines. The adoral adambulaeral plates 

 usually three in contact behind the oral plates (and the first rather the longest), 

 each carry hut one spine. The large type (station 2851) has two spines on most of 

 the plates on the proximal ball of <■ 



Oral plates small, the spines two or three as in arctica. Where there are two, 

 which seems to be more often, the furrow or smaller marginal is suppressed. In the 

 type each pl..,te has a si, oil lapei in- blunt spine at the inner end and another, the 

 suboral, at the outer. The latter may carry a large unguiculate pedicellaria, or only 

 one or two crossed pedicellari 



