444 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



spinelets are 2 or 3, nearly equal and divergent. Gray's original 

 diagnosis (1840, p, 281, Echinmter Ellisii) states that the type, which 

 is from South America, has 11 or 12 rays, 15 madreponc todies 

 ("dorsal warts"), and large thick spines. In his generic diagnosis 

 of Echinaster {=Acanthaster, s. s.) he states that the spines are very 

 long and covered with granular skin, and have generally a second 

 articulation about one-third the length from base. This would in- 

 dicate that both his E. ellisii and E. Solaris are large-spined species 

 with high pedicels or tabula, and granules on the spines. 



Family SOLASTERIDAE Perrier, emended. 



Genus SOLASTER Forbes. 



Solaster Forbes, Mem. Wernerian Nat. Hist. Soc, vol. 8, 1S39, p. 120. 

 Type, Asterias endeca Linnaeus. 



SOLASTER TROPICUS Fisher. 



Plate 125; plate 126, fig. 2; plate 133, figs. 2, 2a-&. 

 Solaster tropicus Fisheb, 1913c, p. 221. 



Diagnosis. — Rays 9 or 10; R=145 mm., r=53 mm., E=2.7-f-r; 

 breadth of ray at base, about 35 mm. Disk large, rays fairly broad 

 at base, tapering to a pointed extremity. Pseudopaxillae very small, 

 well spaced, with 4 to 6 small spinelets ; inf eromarginal plates promi- 

 nent, with numerous spinelets increasing very rapidly in size toward 

 the inner or lower end of the compressed, transversely oriented 

 tabulum or pedicel; distal marginals with mostly large spinelets 

 only; furrow spines 5 or 6, rather long; subambulacral spines 5 to 

 7, subequal in length to furrow spines but heavier ; the inner end of 

 the transverse comb is turned aborad, and the innermost spine is 

 shorter than the second; superomarginal paxillae small, alternating 

 with the inferomarginals. Resembling somewhat S. paxillatiLs, but 

 with more numerous furrow spines, less conspicuous subambulacrals, 

 heavier inferomarginal spinelets, less conspicuous superomarginals, 

 and fewer paxillar spinelets. 



Description. — Abactinal surface covered with very small pseudo- 

 paxillae about 0.5 to 0.75 mm. in diameter and spaced 2 to 4 times 

 their width. On the disk they bear 5 or 6 and on the ray about 4 

 small prickly spinelets, united into a fascicular group by membrane. 

 The paxillae are about 0.5 to 0.6 mm. in height and are relatively 

 more widely spaced on the rays than on disk. On the sides of the 

 rays they are arranged in slightly oblique transverse series. Papulae 

 prominent. In each interradiaus midway between center and margin 

 there is a streak or area where the paxillae are sparse. Abactinal 

 plates delicate, 4-lobed in the small specimen but in the type often 

 three-lobed, or in the form of rods. The plates of the lateral por- 



