STARFISHES OF THE PHILIPPINE SEAS. 301 



Specimens examined. — Two, the type and a specimen from sta- 

 tion 5273, off western Luzon, 27 miles southwest Corregidor Light, 

 114 fathoms, mud, shells, and coral sand. 



Remarks. — Dorigona peyitaphylla Alcock from 271 fathoms, Anda- 

 man Sea, is closely related to the present form. Although no figures 

 have been published, I think there is little doubt that the two are 

 congeneric, and possibly even conspecific. 



LITHOSOMA PENICHRA Fisher. 



Plate 76, fig. 2 ; plate 77, fig. 1 ; plate 84, fig. 6 ; plate 85, fig. 1 ; plate 93, 



figs. 6, 6o-&. 



Litliosoma penichra Fisher, 1917&, p. 90. 



Diagnosis. — Differing from L. actinometra in having slenderer, 

 longer rays, narrower marginal plates, restricted petaloid papular 

 areas, and more angular furrow margin to the adambulacral plates, 

 the consecutive pairs of tube feet being separated, beyond base of 

 furrow, as in Nymphaster; surface of plates and encircling granules 

 as in L. actinometra; width of ray at proximal end of first pair of 

 superomarginals (fifth), which meet medially equal to length of 

 first 3 or 3| superomarginals measured on ambitus (5 in L. actino- 

 metra). R=86 mm., r=21 mm., K=4-|-r; breadth of ray at inter- 

 radius, 24 mm., at proximal end of fifth superomarginal, 9.5 mm. 



Description. — Abactinal plates similar to those of L. actinometra 

 except that the median radial plates are wider than long, and to a 

 slighter extent the distal adradials also. The pedicellariae are rela- 

 tively larger, the combined jaws when open being one-third to one- 

 half the diameter of plate, and each jaw is as broad or broader at 

 base than one of the marginal granules, while in actinometra a 

 granule is two or three times as broad as a pedicellaria. Even though 

 the type of actinometra is very much larger than that of penichra^ 

 the abactinal pedicellariae are slightly smaller. The papular areas 

 are petaloid and in extreme width comprise 9 longitudinal rows of 

 slightly elevated plates, leaving a narrow triangular area of flat 

 plates (of about 5 chevrons) free from papulae. Each radial plate 

 has from 15 to 25 four-sided marginal granules flush with the level 

 of the plate. The granules on the corners of the plate are larger 

 than the others. The edge of the plate is sometimes slightly uneven, 

 sometimes very straight. 



From the coelomic side of the abactinal integument the plates 

 are arcuately hexagonal with truncate corners (or have short trun- 

 cate lobes) between which are the circular papular pores. The 

 plates fit tightly together by the lobes, and the surface is strongly 

 convex — very similar to that of L. actinometra. In the interradial 

 areas and center of disk the hexagonal plates fit tightly together 

 and are without lobes. 



