XX 



in a sponge. Now, the Siboga collected a species of Ba/anus at different places in the Malay 

 Archipelago, living also in sponges, and certainly showing great resemblance to B. declivis 

 Darwin. I have thought better, however, observing some differences between Darwin's description 

 of B. declivis and the Siboga-specimens, to describe the latter as a new species, and I proposed 

 for it the name Ba/anus longirostrum. For the present, however, this species may be considered 

 as a representative of B. declivis from the West-Indies. 



But even if we add the latter species to the above list, the number of species found 

 to be distributed so very widely remains a small one, small at least, if we compare it with 

 the great number of species that are known only from the region under consideration. And 

 this warrants us to consider this region as a special province — and this is, as we are well 

 enabled to say now — an especially rich province in the geographical distribution of the 

 Cirripedia. It is certainly true that even a larger number of species, each, however, represented 

 only by few specimens, cannot exercise such a strong influence on the character of a fauna, 

 as a much smaller number of forms that occur in larger quantities will do. Whether from 

 that point of view the barnacles of the coastal region of the Malay Archipelago may stand 

 comparison with those of most other regions of the earth surface, I had no opportunity to 

 make out. But certainly it has been proved, by the investigations of Aurivillius, Borradaile, 

 and Annandale, and of myself with the aid of the Siboga-material, that "India" is much richer 

 in species than Darwin thought it was, and that coral-reefs are not so unfavourable to Cirripedes 

 as formerly was supposed. 



Before leaving this subject I may be permitted to repeat here what I said already in 

 a provisional paper l regarding some results of the investigation of the Cirripedia collected 

 during the voyage of the Siboga. To show that where the depth is more considerable, rela- 

 tively large distances probably separate the places from each other where the animals of a 

 certain species occur, or, that specimens of such a species are never numerous and not to be 

 found at all at very many places, I pointed out that the "Siboga" brought back specimens of 

 only two species of Scalpcllum out of the ten that were collected by the "Challenger" in 

 the Malay Archipelago 3 . That the "Siboga" brought back the only species of Verruca which 

 the "Challenger" brought home from deeper water in that area, would, I said, not be in 

 accordance with this observation in both instances, however, the species was represented 



only by very few specimens. In this connexion I pointed out, that it was astonishing that in 

 several cases, representatives of two and three species of Scalpclluvi, sometimes, moreover, 

 accompanied by a single specimen of a species of Verruca, were obtained with the same haul 

 of the dredge, from the very same locality in consequence. Such stations seemed to be very 

 favourable to the occurrence of these animals; however, of the species found there the same 

 holds good : viz., that they were always collected only in very few specimens. In a footnote I 

 pointed out that the condition of the bottom must be considered of importance in this respect; 



1 Read before the Amsterdam Royal Academy of Sciences at the Meeting of May 30, 1908. 



2 Darwin (A Monograph of the fossil Lepadidae, 1851, p. 6) made the same observation with regard to the fossil species 

 of Hcalpcllum % Pollicipes, etc. : he said "one would naturally have expected, that where circumstances favoured the existence of numerous 

 species of a genus, they would likewise have favoured the multiplication of the individuals in all or most of such species; but this, as 

 we here see, has not always been the case". 



