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seas; finally one species (2. poeclotheca) remains, which is a new species, at present known 
from Japan only. Therefore the number of species occurring in the waters explored by Dorin 
and in the Malay Archipelago at the same time, which really seem to correspond, is not very 
important. Neither is this the case with the species enumerated by Puspry for Japan and 
Bering Sea: he mentions four true species of a/anus together with a so-called subspecies 
(B. rostratus, B. rostratus-apertus Pilsbry (subspec.), B. crenatus, B. cariosus, and B. Ever- 
mannt), but none of these seem to occur in the Malay Archipelago. 
The determination of a sample of Barnacles of the genus La/anus is often a difficult 
task, and is possible only if the material at hand is sufficiently rich to permit of a thorough 
investigation. This, however, is not very often the case with the samples of Barnacles collected 
with the dredge, this being a very haphazard method especially at great depths. Indeed several 
of the new species described in this report, are represented in the collection, submitted to me, 
by one or very few specimens only. With few exceptions, I could not at first go further than 
’ 
to say that the sample “probably’’ belonged to a certain species, and when I attempted to 
determine it more closely, I invariably found it necessary to consider the form as a new species. 
In such cases, I have endeavoured to describe it as fully as possible, and to give several 
accurate figures of itself and its parts, that it will be possible to recognize it readily, should it 
be collected again. I wish to add that, perhaps with a single exception, which I have already 
pointed out, I feel almost certain that the new species will be found to represent as many 
different forms. I think that it is only sufficient detail in description and illustration which gives 
us the right to introduce new species into science; unfortunately such detailed descriptions 
cannot often be given without destroying the specimen, and in those cases in which a new 
species is based on a single specimen, this should be avoided as carefully as possible. 
A question of no smaller difficulty is that of the arrangement of the numerous species 
of this genus into a really natural system. I must confess, that in this respect my work has 
not given me sufficient satisfaction, this was not possible I think because so many typical 
previously described species were not represented in the collection submitted to me which, on the 
other hand, was found, to be rich in new species. The genus Balanus has a world-wide distri- 
bution, being found along the coasts of all the continents and islands of the different zones of 
the surface of the earth. It cannot be wondered at that the species inhabiting such a region as the 
Malay Archipelago form only a relatively small part of the total. For a careful study of the 
relations among the different species, even the material found in all the large Museums of 
Natural History of the world could hardly be judged rich enough. Therefore, what I have 
been able to do in this respect with the Siboga material, has been rather to criticise the existing 
system and to give some indications as to what I would consider a better classification of 
the species. 
The material that Darwin made use of for his classification of this and other genera of 
Cirripedia, came from all parts of the world, and although, as on good grounds can now be asserted, 
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