THE STARFISHES OF THE HAWAIIAN ISLANDS. 
1085 
Linckia diplax (Muller and Troschel ) . 
PI. XXIX, fig. 4; pi. XXXI, fig. 7. 
Ophidiaster diplax Muller and Troschel, System der Asteriden, 1842, p. 40. 
Linckia diplax, Liitken, Videnskabelige Meddelelser, 1871, p. 268. 
Linckia pacifica var. diplax, Sladen, Challenger Asteroidea, 1889, p. 410. 
A large specimen of this species was taken at station 3848, off the south coast of Molokai, to which 
may be added a small specimen from 3872, although the identity .of the. latter is not so certain. The 
large example has 4 arms and 2 madreporic bodies, and its dimensions are as follows: R=138-140 mm.; 
r=10-11.5 mm. ; R = 12-14 r. Breadth of ray at base about 14 to 15 mm.; at widest part, in middle, 
17.5 mm. Ray about 9 times as long as breadth at base measured along one side of ray. Rays are 
considerably flattened in the central portion, narrower at the base and gradually tapering to a blunt 
extremity which is slightly upturned. Papular areas numerous, rather larger than individual plates 
but smaller on the disk. Pores 15 to 25, small. On the lateral face of the arm 3 more or less distinct 
regular longitudinal rows of plates can be distinguished. Between the lowermost of these series and 
the adambulacral plates are 3 longitudinal series of actinal intermediate plates, those of the innermost 
series largest. Granules of the abactinal area very fine, much larger on the convexity of the plate 
than in vicinity of papular pores. On the ventral surface the granules are much larger, polygonal, and 
increase in size toward the furrow. The adambulacral armature is in 2 regular contiguous series. 
The inner series is composed of rather flat, broad, usually spatulate spinelets, with heavy rounded tips, 
separated by a much narrower spinelet about two-thirds the length of the larger. The smaller alter- 
nates more or less regularly with the large spinelet. There may be also a third spinelet, very small, 
almost a granule, in fact, on the aboral end of the plate. This is not common, however. Frequently 
the “smaller” spinelet nearly equals the larger in length but is always narrower and not spatulate. 
The spinelets of the external series are contiguous with those of the inner and are less numerous, 
there being 1 to about every 2 of the furrow spinelets. They are slightly larger than the latter, are 
not greatly flattened, and their tips are thick and rounded. Outside of these there are indications of a 
third rather irregular series which may be easily confused with the general granulation of the actinal 
surface, except that the latter is polygonal, while the larger granules are more rounded. Though 
polygonal at times, they rise slightly above the general surface. 
In the small specimen 3 of the 5 arms are regenerating and the second madreporic plate is almost 
rudimentary. R=33mm.; r=4mm.; R=8r. Breadth of ray at base 4.5 mm. The arms are more 
cylindrical than in the large specimen. Papular areas are much smaller than the surrounding plates; 
pores about 6 to each area. The 3 lateral longitudinal series of plates are distinct. Adambulacral 
armature is as in the large specimen, but the outer or third series is quite distinct. The granulation 
is relatively coarser than in the larger example, and less crowded, especially on the actinal surface, 
so that the granules are globose rather than polygonal. In size this specimen is more nearly like 
Linckia ehrenbergi (Muller and Troschel), to which the papular areas, smaller than the plates, also 
would refer it, but it is probably to be looked upon simply as a young diplax. 
The species which is nearest to L. diplax is L. pacifica, which differs in having but one madreporic 
body. L. ehrenbergi is also very similar, but the arms are shorter (R=7.5 r); also the spinelets of the 
actinal adambulacral series are said by P. de Loriol (Mem. Soc. Phys. et d’Hist. Nat. Geneve, t. xxix, 1885, 
p. 34) to be slightly larger than those of the furrow and equal in diplax. But in the Hawaiian specimen, 
which is out of proportion for ehrenbergi, the actinal spinelets or granules are slightly larger, or at least 
the exposed tip heavier, so that this character is hardly to be relied upon. Linckia mullifora differs in 
the disposition of the adambulacral furrow spinelets, which are separated by a perpendicular series of 
4 or 5 granules. The actinal spinelets are not contiguous with the furrow series, and are of about the 
same size as the latter. The general appearance of the 2 forms is very similar. 
• Perrier (Rev. Stell., p. 145) notes that diplax occasionally has 3 madreporic bodies. 
Localities: Station 3848, south coast of Molokai Island, 44 to 73 fathoms, sand and gravel; 3872, 
Auau Channel, between Maui and Lanai islands, 43 to 32 fathoms, yellow sand, pebbles, coral. 
Linckia multifora (Lamarck). 
Asterias mullifora Lamarck, Animaux sans vertebres, t. ii, 1816, p. 565. 
f Linckia lypus Gray, Ann. N. H., ser. I, vol. v, 1840, p. 284. 
? Linckia leachii Gray, ibid., p. 285. 
Ophidiaster multiforis. Muller and Troschel, System der Asteriden, 1842, p. 31. 
Linckiamultiforas, Gray, Synop. of the Species of Starfishes, 1866, p.14. (Also L.typus and L. leachii.) 
