310 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



ing central tubercular granules on the actinal intermediate plates, 

 and in having the furrow spines stout, often compressed, few in 

 number, with 1 to 3 more or less swollen, enlarged, subambulacral 

 spines. Pedicellariae spatulate, entrenched, usually with denticulate 

 jaws. In addition typical species have the proximal superomarginal 

 plates, increasing in size up to the third, thence decreasing, the third 

 or fourth meeting its fellow medially, the ray being composed, dor- 

 sally, of the superomarginals only. 



SYNOPSIS OF THE SI'ECIES OF ASTROCERAMDS HEREIX DESCRIBED. 



o^. Abactinal plates perfectly smooth, without pedicellariae or central granules ; 

 granules of superomarginal plates on edge of ray only ; subambulacral pedi- 

 cellariae few ; furrow spines proximally strongly compressed. 



lionotus, p. 310. 



c^ One or two, rarely upward of 5, acorn-shaped, tubercular granules on the 

 middle of the abactinal plates ; numerous abactinal broadly spatulate 

 pedicellariae; superomarginal granules scattered over surface of plate; 

 subambulacral pedicellariae more numerous ; furrow spines proximally 

 slender, but markedly compressed sphaeriostictus, p. 313. 



ASTROCERAMUS LIONOTUS Fisher. 



Plate 81, fig. 1 ; plate 82, fig. 1 ; plate 84, fig. 3 ; plate 94, figs. 2, 2a. 



Astroceramus lionotus Fisher, 1933rt, p. 643. 



Diagnosis. — Similar in appearance to A. callimorphus but differ- 

 ing in having less tumid marginal plates, especially on the ray, 

 slightly smaller abactinal plates, and very strongly compressed, 

 bladelike, subtruncate furrow spines; subambulacral pedicellariae 

 slenderer and longer than the actinal intermediate pedicellariae, not 

 similar to them. R=79 mm., r=22 mm., R=3.6 r; breadth of ray 

 at inner end of first pair of superomarginals which meet medially 

 equal to length of first 3§ or 4 superomarginals measured on ambitus ; 

 thickness of disk interradially equal to length of 1^ adjacent supero- 

 marginals. Abactinal plates flat, smooth, except for minute hyaline 

 bosses, and bordered by small granules flush with the general sur- 

 face; superomarginal plates massive, increasing in size up to the 

 third or fourth, which meet medially; margin of ray forming an 

 abrupt right angle, with uneven elevations bearing scattered de- 

 ciduous granules, these encroaching upon surface of plates inter- 

 radially; a few marginal sugar-tongs pedicellariae; inferomarginals 

 slightly and unevenly tumid, with upward of 30 deciduous granules; 

 marginals bordered by a moniliform series of small granules; actinal 

 interradial areas very similar to those of A. caUimorpkus; furrow 

 spines 4 or 5, compressed, and widened at tip ; subambulacral spines 

 2 or 3, heav3\ with proximally, between them a slender spatulate two- 

 jawed pedicellaria ; on outer part of ray subambulacral spine single 

 and much longer than furrow spines. 



