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seas ; finally one species (B. poecilothccd) remains, which is a new species, at present known 

 from Japan only. Therefore the number of species occurring in the waters explored by Doflein 

 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 Pilsbry for Japan and 

 Bering Sea: he mentions four true species of Ba/anus together with a so-called subspecies 

 (/>'. rostratus, B. rostratus-apertus Pilsbry (subspec), B. crenatus, B. cariosus, and B. Ever- 

 iiiannï), but none of these seem to occur in the Malay Archipelago. 



The determination of a sample of Barnacles of the genus Balanus is often a difficult 

 task, and is possible only if the material at hand is sufhciently 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 teel almost certain that the new species will be found to represent as many 

 different forms. I think that it is only sufficiënt detail in description and illustration which gives 

 us the right to introducé 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 sufficiënt 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 Ba/anus 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 difterent 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 



o 



Cirripedia, came from all parts of the world, and although, as on good grounds can now be asserted, 



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