INTRODUCTION 
A large and interesting collection of Cirripedia was made during the cruise (1899—1900) 
of H.M.S. “Siboga” in the Malay Archipelago. The collection is rich in species; they were 
brought together, partly during coast- and reef-exploration, and partly when the bottom of the 
sea was explored with the dredge, the naturalist’s trawl, and other apparatus. A relatively large 
number of the species were found to be new to science; several of the species already known 
were particularly interesting since they were described in Darwin’s Monograph, but have not 
or not very carefully been observed since the publication of that work. 
The material has been worked up to a large extent for the determination of the species, 
and secondly for the study of their geographical and bathymetrical distribution. Although the 
collection was a rich one, only very few species, and not always the more interesting ones, 
were represented by specimens sufficiently numerous to provide materal for anatomical research; 
moreover, although the state of preservation of the material was generally good for microscopical, 
histological and other research, it could not, of course, be compared with fresh material, as this 
can now be had and investigated in marine stations all over the world. Consequently, details 
of the animal’s structure were examined and the results inserted in the report, only in such 
cases in which this was useful or necessary for the identification of the species. 
The greater part of the collection was handed over to me towards the end of 1900, 
the rest, in the beginning of 1901. A first instalment of the report (containing the description 
of the Cirripedia Pedunculata) was ready for the press at the end of the year 1906, and was 
published in October 1907; the second part of the report (containing the description of the 
Cirripedia Sessilia: Verrucidae and Balanidae) was finished towards the end of September 1912, 
and sent to the press in October of that year. 
During the cruise through the Malay Archipelago, H. M.S. “Siboga”’ explored that part 
of the Archipelago which is situated to the East of Java, Madura, Bawean Island and Borneo, 
and extends as far north as the Sulu Sea and Talaut Islands, as far east as the Aru Islands, and 
as far south as Rotti Island. The first station was visited on March 7, 1899, the last (N° 323 
on February 25, 1900. At about 100 of the 323 stations, and, moreover, at a dozen coast- 
places, where shore-exploration was carried out, species of Cirripedia were found and collected. 
The total number of species of Cirripedia represented in the Siboga-collection amounts 
