( 113 ) 



an isolation of the different forms. Of course, we cannot express 

 our opinion on this matter with absolute certainty, as dredging, 

 especially in deeper water, always remains an insecure method of 

 testing the greater or lesser commonness of a species at the [dace 

 where it occurs. Yet it is very striking, that in the collections made 

 the species of Cirripeds from deeper water nearly without, an excep- 

 tion are represented by one or by a very few specimens only. Especially 

 when taking into consideration that the pelagic Cirripeds and those 

 living near the coast or in shallow water, are nearly all of them 

 characterised by numerous specimens living in the neighbourhood of 

 one another, we are brought to admit, that where the depth is more 

 considerable, relatively large distances separate the places, where the 

 animals of a certain species occur, from one another, or, that specimens 

 of such a species are never numerous and not to be found at all 

 at very many places. This is also proved by the circumstance, that 

 the "Siboga" found again specimens of two species of Scalpellum 

 only out of the ten which were collected by the "Challenger" in the 

 Malay Archipelago. That the "Siboga" found again the only species 

 of Verruco which the "Challenger" brought home from deeper water 

 in that area, would not be in accordance herewith — in both cases, 

 however, that species was also represented by very few specimens 

 only. Finally, it seems astonishing in this connection that in several 

 cases representatives of two and three species of the genus Scolpellum, 

 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 seem to be very 

 favourable for the occurrence of these animals: however, for these 

 found there the same holds good, viz., that they were collected in 

 very few specimens only l ). 



For some deepsea-species of Scalpellum it was possible to make 

 out, that they produced only a few but relatively large eggs, and 

 that their metamorphosis was an abbreviated one. There is good 

 reason to suppose that these peculiarities are of importance for the 

 question of their scarcity — we cannot say, however, that the one 

 is explained by the other. Nevertheless, so far as our knowledge 



l ) It is obvious to admit, that the condition of the bottom in such cases is all- 

 important. Without denying it. we must point out, however, that to judge from 

 the information regarding the condition of the bottom as given in the list of the 

 stations, its importance for the distribution of the Cirripediu is by no means so 

 apparent as might be expected. So we can well say that many species of Scalpel- 

 lum were found at places where the bottom was muddy, but several other species 

 were obtained from a bottom of hard sand, of coarse sand or of coral sand etc. etc. 



8 



Proceedings Royal Acad. Amsterdam Vol. XI. 



