SHALLOW-WATER STARFISHES 145 



Genus Stenasterias Verrill, nov. 

 Type, S. macropora Verrill. 



Rays slender, six in the type. Dorsal plates are wide, lobed, imbri- 

 cated, stichasterial in arrangement. Median radial row and dorso- 

 lateral rows are nearly regular. 



Both marginal rows are formed of wide imbricated plates. One 

 row of small peractinal plates, and a short subactinal row. All these 

 plates are closely covered with clusters of minute spinules. Papular 

 areas small; papulae few, often isolated. Adambulacral and ambu- 

 lacral plates not strongly compressed. Ambulacral pores unusually 

 large, in four rows ; podia large. Adambulacral plates are dipla- 

 canthid. Reproduction unknown. 



STENASTERIAS MACROPORA Verrill. 



Plate L, figure 7 ; plate LXXIV, figure 4 (type) ; plate LXXXIV, figures 5-S 



(details). 



Leptasterias macropora VERRILL, Amer. Journ. Sci., xxvin, p. 65, fig. 10, 1909. 



Disk small. Rays six, long, slender, constricted at base, convex, 

 with a median dorsal row of more prominent ossicles. Radii are 

 3 mm. and 15 mm. ; ratio, 1 : 5. Ambulacral feet and pores unus- 

 ually large; the pores are triangular, overlapping by their acute 

 angles, and separated only by thin plates. Adambulacral plates are 

 strong, unusually thick radially. Adambulacral spines mostly two to 

 a plate, long, slender, tapered, acute or subacute. The grooves are 

 unusually wide and open. A single row of somewhat quadrate, over- 

 lapping interactinal plates, which bear one or two small, rather stout, 

 tapered spines ; a series of small, oblong connective ossicles between 

 these and the adambulacral plates, on the basal part of the ray, each 

 of which may also bear a spine. A row of larger, rhombic, imbri- 

 cated marginal plates, in contact with or overlapping the sides of the 

 peractinal s, runs along the under side of the rays, but curves upward 

 to the dorsal side at the disk. These lateral plates usually bear two 

 or three small tapered spines, like the actinals ; between them and the 

 actinal plates, and between the latter and the adambulacrals, there 

 are only very small spaces, usually occupied by a single papula. 



The dorsal plates are also rather closely imbricated, the spaces 

 between being very few and small, with only one or two papulae ; the 

 median radial plates are thicker and larger, subtriangular, with acute 

 cusps, and concave edges. These overlap, or are imbricated upon, 

 the plates proximal to them, so as to form a median radial ridge 

 or carina. Other dorsal plates are smaller and more irregular. The 

 ii 



