56 BULLETIN 76, TJNITED STATES NATIONAL MUSEUM. 



usunlJy SLX about each paxilla; actinal interradial areas typically very small, 

 with few piLxilhfoim intermediate plates which do not extend far along ray, the 

 inferomarginals and adambulacrals being in contact on the ray proper; inter- 

 mediate plates never extend beyond middle of ray and rarely beyond proximal 

 fourth; arabulacral plates with an angular furrow margin, bearing typically three 

 spines,' of which the midtlle is slightly the longer; two or three rows of spines 

 on artinal surface of plates; first adambulacral plate compressed, much wider 

 than the rest; mouth plates narrow, with inner spines enlarged; tube feet conical, 

 without a tnie sucking disk; no true pedicellariff; anus typically absent; gonads 

 interradial, not extending along ray; superambulacral plates well developed. 



KEY TO THE SPECIES OP ASTROPECTEN HEREIN DESCRIBED. 



a'. A more or less complete series of spines along tipper edge of superomarginals, and frequently also 

 a second parallel longitudinal scries, spaced from the above; central granules of paxillee usually 

 considerably enlarged on disk; enlarged adambulacral spine usually abruptly truncate and 



often sulcate armatus, p. 56. 



a-. Superomarginal plates entirely devoid of enlarged tubercles or spines; central granules or spinelets 

 of paxilla; not enlarged on disk. 

 6'. Paxilla' smaller, about four or five transverse series opposite two superomarginals at base of ray; 

 more or less irregular along radial lines; abactinal plates of papular areas of rays not lobed; 

 upper edge of ambulacral ossicles not produced into a thin lamina between consecutive ampul- 

 lie, and bearing a comb-like series of irregular teeth or spinelets adi/omicus, p. 61. 



6-. Paxilhc larger, about three transverse scries opposite two superomarginals at base of ray; paxillse 

 uniform in arrangement across ray; abactinal plates of papular areas very distinctly lobed; 

 upper edge of ambulacral ossicles curiously compressed and produced into a thin lamina, 

 bearing a few irregular teeth or spinelets; upper end of same ossicles tooihed.. ornatissiiniis, p. 67. 



ASTROPECTEN ARMATUS Gray. 



PI. 5, figs. 1-2; pi. 7, figs. 3, 6; pi. 50, fig. 4; pi. 51, fig. 3. 



Astropecten armatus Gray, Ann. and Mag. Nat. Hist., vol. 6, 1840, p. 181 (not Miiller and Troschel, 

 Syst. Ast., 1842); Synopsis Starf. Brit. Mus., 1866, p. 3.— Verrill, Trans. Conn. Acad., 

 vol. 1, pt. 2, 1867, p. 332. 



Astropecten erinaceus Gray, Ann. and Mag. Nat. Hist., vol. 6, 1840, p. 182; Synopsis, 1866, p. 

 3. — Verrill, Trans. Conn. Acad., vol. 1, pt. 2, 1867, p. 332. — Perrier, Revision des 

 Stell^rides, 1875, p. 358. — Sladen, Challenger Asteroidea, 1889, p. 734. — Fisher, Proc. 

 Wash. Acad. Sci., vol. 8, 1906, p. 118. 



Astropecten orstedii Lutken, Vid. Medd., 1859, p. 159. — Verrill, Trans. Conn. Acad., vol. 1, pt. 

 2, 1867, pp. 274, 328, 330. 



Diagnosis." — Size frequently large. Rays five. R = 129 mm.; r=30 mm.; 

 R = 4.3 r. Breadth of ray at base, 32 mm. Species variable in relative dimensions 

 and in ornamentation. Sides of ray rather high, vertical. Marginal plates massive, 

 the superomarginals encroaching more or less onto abactinal area, and usually 

 armed with one or two short stubby spines, placed one above the other antl forming 

 two longitudinal rows of spines along ray except at base, where they may be as 

 many as four si)ines to a plate, and at tiji, where there is usually but one. Great 

 variation in this respect; frequently only one series of spines, or rarely only a few 

 scattered. Paxilla; fairly large, the central granules or spinelets larger than 



oProm a specimen in the Stanford collection, collected by E. C. Starks at San Diego, California, 

 figured on pi. 5, fig. 1. 



