( 114 ) 



now goes, we must consider the deepsea-species of Scalpellum 



and Verruca as hermits ; as the number of species of these genera 

 especially is very large, most probably they furnish precious evidence 

 for the ideas, about the influence of isolation on the origin of new 

 species, which were brought forward originally by Moritz Wagner 1 ) 

 and were criticised and adopted in a much modified form only by 

 Weismann 2 ). 



For the geographical distribution of the Cirripeds the study of 

 those collected by the "Siboga" lias also been very instructive. With 

 the exception of the pelagic forms, which are found attached to 

 floating objects : pieces of wood, vessels, animals swimming at the 

 surface: Cetaceans and others, etc. etc. and many of which are found 

 in various parts of the world, these Crustaceans live attached to 

 stones, shells of molluscs, corals etc. ; the latter have good oppor- 

 tunity for active locomotion only in larval condition. But even in 

 that condition, in consequence of their nearly microscopic size, their 

 activity is only very limited ; Nauplius- and Zoëa-larvae have limbs 

 which enable them to move about, but more important is no doubt 

 the distribution they are subjected to in a passive way, i. e. by 

 means of the currents. However, even the latter distribution as a 

 rule seems to be a very limited one : we only know very few non- 

 pelagic Cirripeds which have a world-wide range or which occur in 

 several of the eight provinces which were proposed by the present 

 author in his Report on the ''Challenger - ' Cirripeds for the animals 

 of this group. The East-Indian or Malay Archipelago combined with 

 the Philippines, Malacca, New-Guinea and the East coast of (British) 

 India is one of these provinces ; the investigation of the "Siboga"- 

 material has shown again that this province indeed possesses its own 

 Cirripeds, with the exception only of those species, which so to 

 say spread themselves over its boundaries into other provinces, per- 

 haps also of a few species which are at home in an adjacent pro- 

 vince and came over its frontiers into the Malay Archipelago. Of 

 the deepsea-Cirripeds we only know one single species, which can 

 be said to occur at widely distant places of the earth's surface : 

 Scalpellum acutum. The "Challenger" collected this species in the 

 Atlantic Ocean (near the Azores) and in the Pacific (near the Kermadec- 

 Islands) at a depth of 940-1800 in. ; the "Talisman" also in the 



!) Wagner, Moritz, Die Darwin'sche Theorie und das Migrationsgesetz der 

 Organismen. Leipzig, 1868. 



2 ) Weismann. August, Ueber den Einfiuss der Isolirung auf die Artbildung. 

 Leipzig, 1872. 



