202 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



Remarls. — This species is occasionally caught by fishermen in Monterey Bay 

 and Puget Sound. Its Ufe colors are very bright. It seems to inhabit several 

 kinils of bottom ranging from rocl<s and shells, hard sand, gravel, clay, and pebbles, 

 to green mud, and a mixture of mud and rocks. 



MEDIASTER TENELLUS Fisher. 

 PI. 3G, figs. 1, 2; pi. 57, figs. 3, 3a-(/,- pi. 59, fig. 2. 

 Mediaster tenellus Fisher, Bull. Bur. Fbheriea for 1904, vol. 24, June 10, 1905, p. 307. 



Diagnosis. — Rays five. R = 58 mm.; R = 19 mm.; Il = 3r. Breadth of ray 

 between first and second superomarginals, 20 mm; at middle of ray, 7 or 8 mm. 

 General form flattened ; disk large ; rays fairly long and slender, tapering abruptly at 

 base, then more gradually; interbrachial arcs very wide, and rounded; abactinal 

 surface inflated on radial areas, sunken on interradial areas, tlie rays especially 

 being convex; actinal surface considerably inflated on disk; marginal ])late small, 

 confined nearly to sides of body; abactinal area with tabulate plates or parapaxiUje 

 having an ornate crowTi of numerous prismatic spinelets, and often a smaU upright 

 two-jawed pedicellaria; adambulacral plates Avith five long strongly compressed 

 furrow spinelets, and three actinal spinelets about three-fourths as long; a few 

 adambulacral and actinal intermediate pedicellari?e -with liigh slender jaws. Rudi- 

 mentary superambulacral i)lates present; internal ossicles connecting abactinal 

 plates of papular area; papulte single. 



Description. — Abactinal area covered with ornate, regularly spaced para- 

 paxillse or tabulate plates, largest in a regular median radial series, decreasing thence 

 toward tip of rays and margin of disk; paxillffi of median radial series elongated 

 transversely, the others roundish; the former bearing on the peiiphery of the tabu- 

 lum fifteen to seventeen prismatic, blunt spinelets, as long as, or shghtly longer 

 than, the lesser dimension of the tabulum and decidedly longer than is usual m tliis 

 genus; in the center are six or seven irregular, prismatic, pointetl granules, much 

 shorter than the peripheral spinelets; ornamentation of the other iiaxillse differing 

 only in having fewer spinelets and granules. At the tip of the ray the plates lose their 

 tabulate character. Many of the paxillse bear on the edge or nearer the center, a 

 small upright pediceUaria, whose two broadly spatulate concave jaws are shghtly 

 higher than wide and very mucli larger than the central granules. They are nearly 

 as long as the marginal spmelets, and curve inward slightly toward each other. 



Abactinal plates, viewed from the coelomic side, are seen to be well spaced, 

 transversch' elliptical or roundish with slight indications of lobing. The median 

 radial plates are considerably wider than long. All plates of the papular areas are 

 connected by internal radiating ossicles, but these are less regular than in sequalis. 

 Between the ratlial and either ad radial series there are sometimes two or even three 

 shorter ossicles end to end. There is only one conspicuous papula to an area, not 

 two or three as in sequalis. They are absent from the tip of rays and a small inter- 

 radial triangular area adjacent to the marginal plates. 



Marginal plates rather smaller than in any other species of the genus, and 

 throughout most of the ray the superomarginals are confined to the side wall; 

 thirty in number from median interradial line to extremity of ra.v, thin, slightly 



