ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 89 



prismatic also, and square tipped. More often the central spinelcts are only slightly 

 heavier than the peripheral; or one or two may be enlarged, and the rest graded in 

 size up to these. Between these actinal paxillre are deep channels leading from the 

 marginal grooves to the furrows. The plates, from which the carinations spring, 

 are seen to imbricate very strongly when viewed from the coelomic side, the outer 

 end being often prolonged. Considered from the external surface the latter lies 

 under the inner end of the adja(;ent plate (in interradial direction). 



Madreporic boily large (about 9 or 10 mm. in diameter), undulating in outline 

 and hidden by large paxilhu situated on its surface (about eighteen). It is situated 

 a little adcentrally to the middle of the minor radius. 



Color in life: Abactinal .surface orange yellow, actinal surface lighter yellow. 



Anatomical notes. — Superarabulacral plates are present as slender rods, slightly 

 flaring at tips, which pass from outer eml of ambulacral plates to the first or inner 

 actinal intermediate plates; absent from first two plates, and very small near tip of ray. 

 Gonads, in the form of closely placed dichotomously branched tufts, depend from the 

 genital stolon, extending in a series half the length of ray. Each genital tube con- 

 sists of two main branches and two or more terminal branchlets. In the specimen 

 examined they pack the coelom full. These genital stolons are situated on either 

 side of the median radial area slightly less than midway to margin of paxillar area. 

 Anal aperature prominent, with a narrow periproct. It is connected by a short 

 intestine with the large single sack-like intestinal coecum lying in the left radius of 

 trivium. The lining of the coecum is traversed by small folds or corrugations. 

 Directly under the anal aperture of caecum is a slit about 2 mm. long opening into a 

 very short intestine, which leads into the stomach. The latter has much folded 

 walls, and these appear to be no diilerentiation into dorsal and ventral divisions. 

 Hepatic cceca are large with a spacious interior, which is pinnately divided into simple 

 side pockets with more or less folded walls. A large Polian vesicle in each interra- 

 dius. Tiedemaiin organs, two to each interradius, large, and with many fine 

 divisions. Interradial septa single, without calcareous bodies. Stone canal very 

 large. Tube feet large, conical, without calcareous rods in the walls. 



Variations. — In medium-sized examples — that is, with R equal to about 70 

 mm. — the rays are not so broad on the outer part; consequently they seem to 

 taper more evenly. The actinal interradial areas are also smaller, and on outer part 

 of ray there are not so many intermediate plates. The abactinal paxillse are not so 

 crowde^l, nor of course so large. Irrespective of size there is a slight variation in 

 marginal plates. The inferomarginals project laterally beyond the superomarginals 

 in a varying amount, and the spines or tubercles are bluntly pointed in some speci- 

 mens, in others clavate ^vith truncate or concave tips. Some specimens have as 

 many as three superomarginal tubercles, especially on outer part of ra}', where they 

 are longer than proximally. The actinal intermediate i)axilhe are rather variable, 

 the central spinelcts being usually slender (but stouter than the peripheral) and 

 slightly spaced on the keel or tabulum of plate; a very few .tpecimens (two or three) 

 have the central spii>elets conspicuously thicker than the perij)heral ones, polygonal 

 in section, with truncate tips, these being graduateil in size from one or two central 

 spinelcts to the peripheral. The spinelcts on surface of mouth and ailambulacral 

 plates are also variable in arrangement. 



