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4. Tetraclita coerulescens (Spengler). 
DARWIN, CH., Monograph. The Balanidae, Verrucidae etc. 1854, p. 342, pl. XI, fig. 4a—ad. 
A depressed-conical, rather large specimen of this species was taken at Banda when 
the reefs were explored. Its surface is strongly corroded, the longitudinal ridges are here and 
there visible, and a good deal of the infilled parietal tubes are exposed. The colour is greenish- 
blue, and whitish between the darker spots and ribs. The shape of the basis is irregularly 
oval, its longest diameter measures about 40 mm. 
The structure of the inner side of the scutum is so characteristic that no doubt remained 
as to which species the much-corroded specimen belonged. 
This species seems to occur at different places in the tropical Eastern Seas: Pacific 
Ocean and Philippine Archipelago (Darwin and “Challenger’’), Amboina, Larentuka and Singapore 
(WELTNER), Banda (“Siboga’’). 
Genus Pyrgoma Leach 
Darwin (1854) enumerates and describes 9 species of this genus, and no new species 
have been added to the list since the publication of his Monograph. WeLTNER! (1897) pointed 
out that a Pyrgoma collected (in 1874) by HitcenporF in the Bay of Yeddo (Japan), though 
nearly related to P. cancellatum (Leach), differs from that species in several respects, and was, 
in consequence, considered by him as forming a variety for which he proposed the name 
P. cancellatum var. japonica Weltner. The author intended to give a full description with 
figure of this variety, but, so far I know, it has not as yet been published. 
Nor has our knowledge with regard to the geographical distribution of the other species 
of this genus made great advances, the different cases mentioned by We TNER in his ‘Ver- 
zeichnis” being the only ones which came to my knowledge. 
Therefore we only know of the following species as occurring in the 6'* Province, including 
the Malay Archipelago: 
Pyrgoma anglicum Sowerb. Singapore, according to WELTNER. 
Pyrgoma grande (Sowerb. Jr.) Singapore and East Indian Archipelago (Darwin), Birara 
(Neu Pommern) (WELTNER). 
Pyrgoma milleporae Darwin. Philippine Archipelago (Darwiy), Birara (Neu-Pommern) 
(WELTNER). 
Pyrgoma crenatum Sowerb. Philippine Archipelago, Singapore (Darwiy), New Guinea 
(WELTNER). 
Pyrgoma monticulariae J. E. Gray. Singapore (Darwiy). 
During the cruise of H.M.S. “Siboga” specimens of three species of Pyrgoma were 
collected in the Malay Archipelago: one sample consists of numerous specimens of Pyrgoma 
1 WELTNER, W., Verzeichnis u.s. w. Archiv f. Naturgeschichte. 1897. Bd. I. 5, 227- -280. 
w 
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