1894. PROCEEDINGS OF THE NATIONAL MUSEUM. 265 



Of the upper marginal plates there are 8 on each radial margin, and 

 of tlie lower plates, 9, including a very small one next the apical plate. 

 The larger plates of the upper series are nearly rectangular in outline, 

 but rather higher than long; as they approach the end of the rays they 

 become relatively shorter, until, near the end of the ray, the leugth is 

 about one-half the height. The inferior plates are about equal in size 

 to the upper, and stand nearly ox)posite to them, but the sutures do 

 not correspond closely; the larger part of their surfaces extend upon 

 the actinal side of the interradial region. The entire surface of the 

 plates of both series is densely covered with small polygonal granules, 

 except a small, rounded, or oval, bare spot on the upper end of each 

 su])erior plate, and near the lower margin of each inferior plate; but 

 these smooth bare spots are occasionally wanting, and vary in size, 

 indicating that they may have been caused by injury before capture, 

 for the plates are pitted where the granules have subsequentlj^ been 

 removed. 



The large interradial areas of the actinal side are occupied by a close 

 pavement, mostly of rhombic plates, which are mostly arranged in rows 

 parallel to the ambulacral groove. Each plate is covered by a compact 

 group of angular granules, usually 10 to 15 on each plate ; these granules 

 are coarser and more elevated than those on the surface of the mar- 

 ginal and dorsal plates, but they are all similar and of the same height, 

 producing a very even surface. The adambulacral plates are arranged 

 in 3 nearly regular longitudinal rows; the furrow-series consists usu- 

 ally of 3 nearly equal spines which are moderately stout, not very long, 

 mostly flattened, and obtuse ; the next series is formed by 2, somewhat 

 flattened, blunt spines, side by side, on the actinal side of each platej 

 these are a little shorter, and decidedly stouter than the furrow- series; 

 the outer series is formed by 3 small, equal, angular, granule-like spi- 

 nules on the outer margin of each plate; they are similar to and only 

 slightly longer than the granules of the adjacent plates. The jaws bear, 

 on each side, a row of 8 or 9 rather stout and short angular spines of 

 which the innermost are a little the largest and also a row of similar 

 spines, of about the same size, on each actinal border, with a few 

 smaller ones in a group at the distal end. The jaws have no distinct 

 actinal keel. 



This species was taken by the steamer Albatross in 1883, off La Have 

 Bank, at station 2064, N. lat. 42° 25' 40", W. long. 60° 08' 35", in 122 

 fathoms, and in 1885 off Nova Scotia at station 2507, N. lat. 44° 27' 30", 

 W. long. 62° 33' 30", in 80 fathoms. A single specimen was obtained 

 at each locality. 



This species is closely allied to P. granularis, which is also found in 

 the same region. The latter differs in having the interradial margin 

 more regularly incurved, with the rays relatively longer and more reg- 

 ularly tapered and the tip less acute, owing to the smaller size of the 

 apical plate; the granulations of the abactinal marginal plates are also 



