420 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



of the actinal intermediate plates which are not in chevrons, in the 

 ordinar}^ sense, but form transverse series, separated by shallow 

 grooves, proceeding from the adambulacrals to the ambitus. The 

 first few series do not reach the ambitus, but end rather irregularly 

 on the inner half of the interradial line. This may be true to a cer- 

 tain extent in Asterina, but its plates, as in Nepanthia, form series 

 more obviously parallel to the adambulacral series. In Paranepan- 

 thia the spinelets of the actinal intermediate plates are in bunches or 

 tufts near the furrow but pectinate toward the margin. Nepanthia 

 differs in having the rays slender and cylindrical, or narrow, flat- 

 tened actinally and arched abactinally (hemicylindrical) with a cor- 

 respondingly nar)-owed actinal intermediate area, the plates of which 

 have numerous short spinelets like the abactinal plates. 



CaUopatiria Verrill ^ differs in lacking the differentiation of the 

 abactinal plates into 2 areas, in having the adambulacral armature 

 more nearly like that of Asterina, and in having many small second- 

 ary abactinal plates. 



Paranepanthia seems to me to include N. hrachiaia Koehler (1910a, 

 p. 133), a six-rayed species from the Andaman Islands. 



PARANEPANTHIA PLATYDISCA (Fisher). 



Plate 114, figs 1, 4 ; plate 116, figs. 4, 5 ; plate 132, figs. 1, la-h. 



Nepanthia platydisca Fishee, 1913c, p. 218. 



Diagnosis. — Rays 5- 11=54 mm., r=23 mm., R=2.3 r; breadth of 

 ray at base, 36 mm. ; interbrachia rounded, rays tapering evenly from 

 base to bluntly pointed extremity ; general form much flattened and 

 resembling an AsteHna with thin disk: edges of disk and ray thin; 

 abactinal plates divided into 2 areas, a median radial, where the 

 plates are irregularly distributed, and lateral areas, where the plates 

 form transverse (and also to some extent longitudinal) series, the 

 transverse with about 26 or 27 plates at base of ray ; plates resembling 

 small flat-topped pseudopaxillae ; actinal intermediate plates small, 

 in transverse series, the larger plates with 15 to 20 slender, very sharp, 

 webbed spines; furrow spines 7 or 8, webbed into a very convex 

 fan ; subambulacral spines 12 to 20, also webbed. 



Description. — ^The general form is flat, the body being thin, much 

 as in Anseropoda. The radial areas of irregularly arranged plates 

 are sharply marked off and their width at base of ray is about one-half 

 r, while on the interradial line they occupy a trifle more than one-half 

 r. Between the margin of the median area and the ambitus extend 

 transverse series of small elliptical plates, which also, on the adradial 

 half or two-thirds of this area, form longitudinal series. The trans- 

 verse series sometimes bifurcate at the outer ends, and the plates of 



1 CaUopatiria Verrill, May, 1913 ; type. Patina bellula Sladen. Amer. Journ. Scl., 

 vol. 35, p. 480. 



