208 A. E. Verrill — Revision Genera and Sx^ecies of Starfishes. 



than broad, and separated by deep sutural grooves. They are de- 

 cidedly larger than in O. hispidus and not so square. The upper 

 and lower ones correspond closely in size and position, so that the 

 sutural grooves are continuous. Large examples have about 35 in 

 each series on each side of the body. 



In some specimens as many as five or six of the distal dorsal mar- 

 ginal plates are in contact medially ; in others all are separated, the 

 abactinal plates reaching even the apical plate. 



The marginal plates, above and below, are thickly covered with 

 large numbers of small, slender, acute spinules, those near the mar- 

 gins divergent and forming fascioles. The spinules of the upper 

 plates are rather smaller and more numerous than those of the lower 

 ones, but there is no such difference in character as in 0. hispidus. 

 When the spinules are removed the plates are thickly covered with 

 minute tubercles. 



The abactinal radial plates are well separated, small, paxilliform 

 with a rounded, convex or capitate top, covered with a cluster of 

 slender, acute, setiform, divergent spinules. 



The papular pores are large and conspicuous and occupy large 

 areas; they are placed singly. The actinal plates are rather numer- 

 ous, rhombic, finely tuberculated, arranged in three or four rows 

 parallel with the ambulacra ; the first series extends to about the 

 seventh marginal plate. They are covered with dense clusters of 

 slender, acute, setiform spinules, like those of the upper surface 

 but longer. 



The adambnlacral plates are transversely oblong, narrower than 

 the adjacent actinal ones. They bear each thi-ee or four slender 

 furrow spinules in a nearly regular row, and a dense group of 10 to 

 12 or more, somewhat longer, slender spinules on the actinal side. 

 The latter are similar to the actinal spinules, but rather larger and 

 less acute. 



The dentary plates bear marginal and actinal spines, similar to 

 those of the adambulacral plates, but those at the apex are shorter, 

 prismatic and blunt, while there are usually two or three near the 

 sides that are larger than the rest and somewhat curved. The plates 

 are separated by wide sutural grooves. 



The recurved spines are compressed and often somewhat curved ; 

 the distal end is hyaline, suddenly narrowed or acuminate, and 

 usually very acute. 



One of the larger specimens has the greater radius 37"^"" ; lesser, 

 IS"^"'. Another has the greater radius 32™'"; lesser, IV"™. 



