124 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



monly alternate plates are spineless, but specimens occur in which several consecutive 

 plates bear spines. There are about 30 plates in the series when R is 55 mm. The 

 dorsolaterals, irregularly three or four lobed, are in a zigzag series as a rule and are 

 connected together (and with the carinals and superomarginals) by one or two slender 

 elliptical ossicles of different lengths. The superomarginals are the largest plates, 

 somewhat arcuately kite-shape in form, 32 in number when R is 55 mm., and over- 

 lapping rather strongly. There is a conspicuous area of hyaline protuberances on the 

 lateral surface, larger on the alternate, regularly spineless plates. The inferomarginals 

 are a little smaller than the superomarginals, but the ascending lobe is shorter than 

 (and is covered by) the descending lobe of the superomarginal. The lower border 

 of the inferomarginals is rather rounded and thickened, the two spines being on a 

 very slight lobe. The actinal plates are small, flattened, a little higher than long, 

 and placed with the edge outward. The marginals are relatively smaller than in 

 Sclerasterias heteropaes. The actinostomial ring (pi. 56, fig. 3) is fairly stout, but 

 not quite so strong as in Stylasterias Jorreri. The enlarged inner end of the ambu- 

 lacral ridge is as long as the six following plates. The first ampulla pore is larger 

 than the three following pores which form an unequal triangle. The interbrachial 

 septum is very short on account of the relatively small size of the disk. The ambu- 

 lacral plates are more compressed than in Sclerasterias heteropaes, there being in the 

 space of 10 mm. at base of ray 19 or 20 plates while in the comparable equal-sized 

 type of heteropaes there are 16. The plates are about as much compressed as in 

 Orthasterias Tcoehleri. The pores are smaller than in Sclerasterias, have very flaring 

 lips, and the two series are more widely separated — but there is variability in this 

 feature. 



Viscera. — Intestinal coecum with three branches, two about 10 mm. long, 

 without subdivisions, and the third with six short branches. Dorsal stomach small; 

 hepatic coeca slender, reaching nearly to end of ray, ventral stomach spacious, with 

 strong retractors. Gonads large, reaching nearly to end of the ray. Each consists 

 of a fairly stout axis with numerous small lobules on the side toward marginal plates, 

 and numerous rather long tapering irregularly lobulated branches on the mesial side. 

 Each gonad opens on a level with the superomarginal plates near interradius. 

 Ampullae single, but broad and incipiently two-lobed when partly contracted; 

 no Polian vesicles; tube-feet rather large, crowded. 



Young. — The smallest specimen from La Jolla has R 22 mm., breadth of ray 

 at base and r, 3.5 mm. The rays are slender and scarcely tapered until near the tip. 

 The spines are relatively long and crossed pedicellariae few. On the base of each 

 ray, dorsally, are two to four very slender, lanceolate acute straight pedicellariae 

 which appear relatively large though only 0.6 to 0.7 mm. long, and there are several 

 other quite tiny ones scattered over the disk and rays; others a little larger occur in 

 the interradial angles laterally and below. Four or five similar to the larger dorsal 

 ones, but a little less slender, occur in the intermarginal channel. These seem to be 

 the large spatulate denticulate pedicellariae of the adult, in the process of develop- 

 ment, and this is the only very young specimen in which I have observed them. 

 No visible actinal plates. Only a few distal adambulacrals with one spine. Furrow 

 spines relatively long and slender. One pair of contiguous adambulacral plates 

 behind the mouth plates. The carinal, dorsolateral, and marginal spines are in quite 



