XX 
in a sponge. Now, the Siboga collected a species of Balanus 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 Balanus 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 Aurtvitiius, 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! 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 Scalpellum out of the ten that were collected by the ‘Challenger’ in 
the Malay Archipelago”. 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 Scadpellum, 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 Scalpellum, 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”. 
