86 THE ECHINODERMS OF TORRES STRAIT. 
merely an extra actinal series of these areas on each side, but when typically developed 
this extra series contains twice as many areas as do the other series. Associated with this 
development of the actinal surface, there is more or less of a tendency to have the rays 
widened at the base and somewhat trigonal there. 
Although a small group and little known, Hacelia seems to be distributed throughout 
the tropics except only the west coast of America and the Pacific Islands. The genotype 
is the only species of which we know anything about the color in life or about its habitat 
and natural history. Two of the other three species are known from only a single speci- 
men each. 
Key to the Species of Hacelia.” 
Furrow spinelets unequal, adoral distinctly wider; pedicellarie usually present, at least on actinal surface 
in adults. 
Rays tapering steadily from distinctly widened base; adoral furrow spine little wider at tip than at 
base; pedicellarie with sides of alveolar pit not conspicuously thickened or swollen .......... attenuata 
Rays more cylindrical; adoral furrow spine very much wider at tip than at base; tip thick and 
rounded; sides of alveolar pit of pedicellaris more or less conspicuously thickened or greatly 
swollen}: <.xcsijerceitis Severe, cops chon eee Makin wate aiaYonove eubvausleie tie oakys Seeastaols rotor ateons helicosticha 
Furrow spinelets equal; no pedicellariz. 
Distalmost marginal plates covered with granules, of which one or more central ones are more or 
less enlarged; granulation rather coarse, about 15 to 20 per square millimeter on actinolateral 
plates HR = GiSin == Pyaneyaslab recess SG rd.a ie the Baeabenat tet orshepeie rors ede eee CE ee reece inarmatus 
Distalmost marginal plates bare and somewhat swollen at center; granulation finer and smoother, 
about 25 to 40 granules per square millimeter on actinolateral plates; R=5.8 r=............. superba 
Hacelia attenuata. 
Ophidiaster (Hacelia) attenuata Gray. 1840. Ann. Mag. Nat. Hist., 6, p. 284. 
Hacelia attenuata Ludwig. 1897. Seesterne des Mittelmeeres, p. 272, pl. 3, figs. 6, 7; p. 11, figs. 1-17. 
Nothing I can say would add to Ludwig’s account of this species, known only from 
the Mediterranean and at the Azores. The largest specimen seen by Ludwig had R =150 
mm., but this was exceptionally big. 
Hacelia helicosticha. 
Ophidiaster helicostichus Sladen. 1889. Challenger Ast., p. 405, pl. Ixix, figs. 5-7. 
Hacelia helicostichus H. L. Clark. 1909. Bull. M. C. Z., 52, p. 111. 
I have already pointed out (1909, lc.) that Bell’s ‘‘Linckia nodosa,” of the Alert 
report, is really Sladen’s fine species. Of course, since Sladen’s species was not described 
for five years after the Alert report appeared, it is not strange that Bell failed to recognize 
the species, but why he should have ever supposed his specimens were Perrier’s L. nodosa 
I do not understand. It is obvious that the reason Sladen did not note the close relation- 
ship to H. attenuata was because he overlooked the actinal series of papule. The two 
species are really much alike and the differences are not at all striking. Sladen’s failure 
to detect the actinal series of papule between the actinolateral plates was no doubt due to 
his failure to dry the specimen, for the areas in these series contain only 1 to 3 papule 
each and they are often undeveloped, so that the series is not regularly continuous, and 
unless the specimen is well dried they are very hard to make out. 
As yet, helicosticha is known only from the western end of the Torres Strait region, 
the Arafura Sea, Holothuria Bank, and northwestern Australia. The Herdmans’ record 
from Ceylon (1904, p. 145) is too dubious to have any weight. Koehlers’ record from the 
Sunda Islands refers to the following species, inarmata. Bell’s suggestion (1894) that his 
Linckia megaloplaz is probably the young of H. helicosticha is not unnatural but, as Koehler 
suggested (1895), it is quite certainly wrong as the two forms are not nearly related. While 
the type of helicosticha had R =130 mm., Bell (1884, p. 124) records (as Linckia nodosa) a 
specimen with R=213 mm. Nothing is known of the color in life. 
