Hi 



II 1 1KTIN 76, I V1TED STATES NATIONAL MUSEUM 



station 3244, Bristol Bay, 4.5 fathoms, these pedicellariae arc 0.25 to 0.315 mm.; 

 in mi example from station 3242, 11 fathoms, 0.27 to 0.315 mm.; in a specimen from 

 3248, 21 fathoms, a maximum of 0.315 mm.; Popoff Strait, Shumagin Islands, low 

 water, 0.27 to 0.315 mm. These measurements arc in agreement with those of 

 crossed pedicellariae of comparable specimens from Petropavlovsk, Port Clarence, 

 and Norton Sound. The larger crossed pedicellariae are therefore a characteristic of 

 deep water specimens as they are of the thick-spined forma anomala. 



• ih stages und i/oung (pi. 5). — The change in form due to increase in size is 

 shown by the following measurements of specimens from stations 3241 and 3242. 

 'Ph.- younger stages have both narrower rayed and broader rayed forms: 



The ratio between K and the breadth of the ray at the widest part, close to the 

 base, varies from 3.4 : 1 in No. 1 to 2.8 : 1 in No. 11. Xo 5 is a broader rayed form, 

 while 4 and ti have relatively slenderer rays. In specimens of the size of No. 8, and 

 larger, the proximal third of the ray increases more rapidly in width relatively than 

 does the distal portion, so that the difference in appearance with increasing age is 

 more marked than the figures seem to indicate. With the broadening of the rav at 

 the base the intermarginal channel makes its appearance and quickly widens, leaving 



■ also for an actinal channel. The presence of these regular channels is one of 

 characteristic features of this species, as of rubens. 



In specimens as small as Nos. 1 and 2 the inferomarginal spines are lateral, with 

 the supermarginal directly above them, the rays being subterete. They lack 

 entirely the characteristic flattened appearance of the adult. In Nos. 5 and 6 the 

 superomarginals are situated a little more laterally than the inferomarginals, while 

 in Xo. 7 the inferomarginals are proximally frankly actinal in position, and the ray is 

 acquiring the characteristic flattened appearance. 



In No. 1 and other small examples the abactinal skeleton has relatively large 

 meshes i naturally much fewer than in large examples) with one or two papulae to a 

 mesh. The abactinal spinelets, 0.3 to 0.4 mm. long, are slender, slightly tapered, 

 not close together and are tipped by several thornlets. Each mostly 3-lobed primary 

 plat.' bears a Bpinelet, but the oblong or elliptical connecting plates are often spineless. 

 In No. 1 there are no abactinal pedicellariae. These appear in No. 2. 



In Nos. 1 and 2. the marginal plat.- are close together, one above another on 

 ih.' -ide of the ray, four lobed, and the lower or descending love of the superomarginal 



rs the dorsal lobe of the inferomarginal as in the various genera allied to Coscin- 



There are our superomarginal and two inferomarginal spinelets and one 



to thn-e forcipulate pedicellariae on them. The intermarginal papular areas are 



v.ry small with a single papula to each. No actinal papulae in No. 1; a few make 



