62 THE ECHINODERMS OF TORRES STRAIT. 
that any Ferdina since collected or described (R =35-42 mm.) it is hard to compare it 
with the other members of the genus, but apparently the relatively very long rays are 
sufficiently distinctive. Pfeffer (1896, p. 43) records a single ray from Tumbatu Island, 
Zanzibar, but (as Ludwig has suggested) one can hardly accept this identification. If the 
arm is really that of a Ferdina, it is more probably flavescens than kuhlit. 
LINCKIA. 
Nardo. 1834. Oken’s Isis, p. 717. 
Genotype: Linckia typus Nardo, l. c. Type designated. It is now generally agreed 
that L. typus = Asterias levigata L., a perfectly unmistakable and well-known species. 
This has long been an exceedingly confused group, to which no fewer than 45 nominal 
species have been referred. As established by Nardo and indorsed the next year by Agassiz, 
it contained 3 species. One of these (variolosa =variolata) was made the type of Nardoa 
by Gray in 1840, and a second (franciscanus) is not identifiable, but the third (designated 
as the genotype by its name, typus) is identical with Linné’s Asterias levigata, a species 
which is fortunately unmistakable, thanks to the fact that the 3 figures to which Linné 
refers do, in this case, all represent the same species of sea-star.1. In 1840 Miiller and 
Troschel added Asterias milleporella Lamarck to the genus, an unfortunate blunder. The 
same year Gray removed variolata to Nardoa and milleporella to Fromia, and added 11 
species to Linckia (see below). In 1842 Miiller and Troschel went to the other extreme 
and abandoned Linckia altogether, dividing its species between Ophidiaster and Scytaster— 
hardly a forward step! Von Martens, in his papers on oriental echinoderms (1865-67) 
returned toward Gray’s conception of the genus by uniting Scytaster and Ophidiaster with 
Linckia. He names 15 species as belonging in the group. In 1871 Liitken added a new 
species, L. nicobarica, to the already unwieldy genus. In 1875 Perrier attempted to bring 
some order into Linckia by a study of the material in both Paris and London, but (much 
of the type-material having been lost) some of Gray’s species were not to be identified. 
However, Perrier discusses 7 of the species previously known and described 2 supposedly 
new ones. In 1885 de Loriol gave some very useful descriptions and figures of the Linckias 
occurring at Mauritius; the colored figures in particular are important. In 1889 Sladen 
gave, in his Challenger Report, a list of the Linckias which seemed to him entitled to recog- 
nition, and this list includes 15 species and 1 variety. Since it was published, only 3 
additions have been proposed, one by Russo (1894), a second by Koehler (1910a) and one 
by H. L. Clark (1914). 
The large series of Linckias in the Museum of Comparative Zodélogy collection has 
enabled me to make a critical study of the genus and I have reached some very definite 
conclusions. In the first place, the earlier descriptions are so brief that they are often of 
little value, and this is particularly true of Gray’s diagnoses. Again, the widely spread 
species show so much diversity in the relative proportions of R, r, and br, that specimens 
often look quite unlike superficially when they are in fact the same. Some of the species 
at least reproduce asexually by autotomy, especially when still of small size, and as a 
result specimens with 4, 6, 7, or even 8 arms occur more or less commonly, and symmetrical 
5-rayed specimens of such species are relatively rare. The number of madreporites is 
equally variable in these forms ranging from 1 to 4; occasionally a madreporite occurs on 
the base of a ray rather than on the disk proper. Color is probably of more value as a 
specific character in the genus than has been previously granted, but unfortunately it is 
very fugacious and of almost no help in identifying museum material. Study on the reefs 
of the living specimens will doubtless show the specific colors in the genus. The size and 
arrangement of the papular areas are subject to growth change as well as to considerable 
1Since both Perrier and Sladen go back to Linck (1733) for specific names, it is not strange that both have 
ignored the tenth edition of the “Systema Nature” with its perfectly definite Asterias levigata. 
