REPORT ON THE ECHINOIDEA—MORTENSEN 13 
are numerous ophicephalous pedicellariae (fig. 3, d@) also resembling 
those of S. durum. In the larger specimen only a single ophicepha- 
lous pedicellaria was found, which looks rather different (fig. 3, 6)— 
not like those of S. durwm. 
The smaller specimen is a beautiful purple, the larger a light 
grayish. 
These two small specimens cannot with certainty be referred to any 
of the species known from the Malay Archipelago. It can only be 
seen with certainty that they belong to the genus Sperosoma, since 
some of the oral ambulacral plates are divided into two in the way 
typical of this genus. It is not very likely that both belong to one 
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FIGURE 8.—Valves of pedicellariae of Sperosoma sp., young: a—c, Specimen from station 
5608; d, specimen from station 5332. a, Valve of tridentate pedicellaria ; possibly the 
edge of the blade not yet fully developed (without serrations) ; b and d, Valves of 
ophicephalous pedicellariae; c, valve of triphyllous pedicellaria. All x 80. 
and the same species, in spite of the fact that both have the peculiar 
are under the valves of the tridentate pedicellariae; the different 
shape of the ophicephalous pedicellariae would seem to preclude the 
idea of their belonging to the same species. That one of them may 
be identical with S. durum is quite possible; but the fact that the 
small specimen, the ophicephalous pedicellariae of which resemble 
those of S. durwm, has the fewer number of aboral ambulacral plates, 
whereas S. durum has, when adult, about three times as many aboral 
as oral ambulacral plates, is not in favor of such identity. That 
S. durum is known hitherto only from the Indian Ocean off the 
African coast—only one specimen is known—would not be any serious 
objection to their identity. 
On the whole, a much richer material, with series of intermediate 
sizes, will be necessary for identifying with certainty these young 
specimens, or for deciding whether they perhaps represent hitherto 
unknown species. 
207447—40-—3 
