H3 
f- enlarj^ed lower pinnules with comparatively sln>rt segments 
whicli have broad longitudinal flange-like processes on the 
outer part of the prismatic ridges Oligometra 
Petasometra A. 11. Clark. 
A. H. Cl.vrk. Smithsonian Miscellaneous Collections, vol. 60, 1912, X" 10, p. 25. 
Die Fauna Sudwest-Australiens, vol. 4, 1913, Lief. 6, p. 311. 
Key to the Species of the Genus Petasometra. 
a' 10 — 14 arms; 20 — 29 (usually 20 — 25) cirrus segments (Flores and 
A m b o i n a clarae 
a^ over 20 arms; 28 — 31 cirrus segments (western Australia). . hclianthoides 
I. Petasometra clarae (Hartlaub). 
Hartlaub. Nova Acta der Ksl. Leop.-Carol. deutschen Akad. der Naturforsch., vol. 58, 1891, 
N" I, p. 41, pi. 2, fig. 19 [Antedon clarae). 
Stat. 50. Bay of Badjo, west coast of Flores. 40 Metres. 3 Ex. 
Stat. 231. Amboina. 3 Ex. 
Of the three specimens from Stat. 50 one has 11 arms 85 mm. long; one IIBr i series 
is present, the IIBr axillary being supported equally by the IBr a.\illary and by the outer side 
of the IBfj; another has 10 arms 85 mm. long and cirri 13 mm. long composed of 20 — 22 
segments; the dorsal pole of the centrodorsal is circular, slightly concave, 2 mm. in diameter; 
the cirrus sockets are arranged in a single regular crowded row; the colour is dark brown, 
the cirri and centrodorsal light yellow brown ; the IBr series and first brachials are white ; there 
are one or two distinct white patches on individual arms; the third has 10 arms 85 mm. long; 
the cirri are VII, 19 — 20, 12 mm. long; the dorsal pole of the centrodorsal is slightly concave, 
circular, 2 mm. in diameter; the cirrus sockets are arranged in a single perfectly regular 
crowded row. 
These specimens differ from the large individual from Amboina in having slighdy fewer 
cirrus segments, and in having P., proportionately smaller; but both of these differences are 
directly correlated with the smaller size. 
One of the examples from Amboina has 10 arms 120 mm. long; the centrodorsal is 
discoidal, the dorsal pole large, circular, slightly concave, 2.6 mm. in diameter; the cirrus 
-sockets are arranged in a single perfectly regular marginal row; the cirri are XIV, 26 — 29, 
17 mm. long, rather stout; owing to the very crowded condition of the cirrus sockets, which 
are all in one regular row, the first segment of the cirri, as viewed dorsally, is very narrow; 
from this segment the cirrus increases in diameter to the fourth, which is at least three times 
as wide as the first, and then tapers almost imperceptibly to the tip; all of the cirrus segments 
are approximately equal in length, short, about twice as broad as long; the lateral margins of 
the segments in the proximal half of the cirri are strongly bent, but those in the distal half 
are straight; be^innincr on the second or third there is a straight serrate transverse ridge, at 
SIBOGA-EXPEDITIE XLlIi5. *3 
