ASTEBOIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 107 



closely appressed to upper end of inferoniarginal plates, bearing on (abulum twenty 

 to thirty polygonal, flat-topped granidos decroasing in size toward peri[)hery, which 

 is surrounded by about forty slentler and, unless seen from side, mconspicuous 

 spinelets, the whole having the exposed surface very Hat. The other paxilise 

 resemble these, but differ in size as indicated above. 



Wlien the abactmal body wall is treatetl with caustic potash and viewed from 

 the inner side the plates or bases of paxillae are seen to be very strongly cruciform; 

 that is, with four lobes. By these processes or arms, which are fairly stout, unta- 

 pered, truncate, or notched at tip, the plates overlap regularly along the four lateral 

 rows of paxilhe, irregularly over median area of disk, where the plates may have 

 three or five lobes each. On the lateral plates the transverse axis is raised into a 

 keel, which, as the plates are in regular transverse rows, forms a transverse ridge 

 about the widtli of four paxillae, the lobes overlapping strongly. Tliis keel is absent 

 from superomarginal j)lates, which have rather wider lobes than the adjacent series, 

 that lobe impinging on the inferomarginals being shorter and rounded. Infero- 

 marginals lobcd also, but those on the longitudinal axis (of ray) very short. Plates 

 on central portion of ray and on center of disk very small in comparison to regular 

 lateral ones. Everywhere on the abactinal surface, in the relatively large spaces 

 between the plates, emerge the papulte, four about each plate. These papulae are 

 compound; that is, the summit is broad and subdivided into man}- papillose subdi- 

 visions, forming a flat-topped group resembling a decalcified low paxilla. 



Inferomarginal plates separated, as usual, by deep fasciolar grooves lined by 

 densely placed capillary spinelets on the outer but not on the umer part. Exposed 

 surface armed with a transverse row of three robust, short, flattened, lanceolate, 

 blunt, or pointed spinesontheouterhalf of the plate, these forming three longitudinal 

 series all along edge of ray; median spine usualty longest (4 mm.) equaling about 

 one-half width of actinal surface of its plate; occasionally umermost longest; 

 outermost spine of series decreasing more rapidly than median as series proceeds 

 along ray, so that at outer part of ray these are reduced to small spiiudets; median 

 and inner spines frequently become broader in proportion to length on outer part of 

 ray, where they very gradually decrease in length. On first dozen plates there are 

 usually four or five spines in each transverse row. Remainder of actinal surface 

 beset with diverse sizes of flattened, blunt, or truncate, rarely pointed, spmelets; 

 two or three m median line larger than rest, more flattened, broader, and usually 

 very blunt or truncate, forming continuation of series of marginal s]>ines. Spinelets 

 become more slender toward edge of exposed surface, grading very abruptly mto 

 capillary spinelets Iming grooves. These actinal inferomarginal spinelets are much 

 longer and larger than the flattened chafT}' squamiform granules of L. brevispina 

 Liitkcn. Abactmal end of jilate with a number of flat-topped granuliform spinelets 

 Lntergrading on the one side with spinelets of actinal surface antl on the other with 

 those of superomarginal paxilla^. Usually just external to outermost margmal spine 

 is a small flattened, sharp, lanceolate sj)inclet, the series of which dies out before the 

 middle of the ray is reached. Terminal plate strongly concave toward paxillar area, 

 crescent-shaped from above, and covered with granules enlarged distally. 



