192 NATURAL HISTORY BULLETIN 



Papular pores are very numerous and are arranged singly, 

 about six around each plate over the whole of the disk and rays, 

 even close to the ends. 



There is no distinct dorsal pore visible, nor do the central 

 plates differ in size from those of the disk in general. 



Marginal plates are small and not prominent. The upper ones 

 are entirely confined to the margin, and are granulated, without 

 spines. The lower ones form the lower part of the margin, but 

 extend also on the disk below ; they bear spinules with a median 

 row of larger spines. 



Interradial actinal areas are large, with numerous plates, the 

 distal ones extending to the distal third of the rays. They are 

 arranged in single radial series, each series usually corresponding 

 to an adambulacral plate and most of them to a marginal plate, 

 but some of the series are short and do not reach the margin, 

 there being more adambulacral than marginal plates proximally, 

 but distally they generally correspond in number, though there 

 are sometimes, locally, two marginals to one adambulacral. These 

 plates are covered with granules, and have divergent, fasciolated 

 spinules along their radial margins, thus forming fasciolated 

 grooves that are coincident with those between the marginal 

 plates. 



The adambulacral plates have a prominent furrow-angle, on 

 which there is a large, median, compressed spine ; at each side of 

 this there are, in the furrow-series, two or three erect flattened 

 spines ; a stout spine occurs on the center of the actinal side, with 

 a single or double row of shorter flat spines back of it. 



The jaws are large, not very prominent, covered with numer- 

 ous short, blunt spinules, and have furrow-spinules like those of 

 the adambulacral plates. 



The only known species of this genus is from the Gulf of Mex- 

 ico, in 68 fathoms. 



SiDERIASTER GRANDIS Vcrrill. 



Sideriaster grandis Verrill, Eevision Genera, p. 220, pi. xx, figs. 8-8fc, 1899. 



Plate xii; figures 5-5&. Details. 



Large, regularly five-rayed, with a broad, somewhat swollen 

 disk, regularly and broadly incurved at the sides. The rays are 

 rather large and rapidly tapered. Greater radii, 133-138™™; 

 lesser, 40™™. Ratio, 1 :3.4. 



