CIERIPEDIA. 149 



year. The definition of the former is " All parts of shell present, heavy, and without 

 pores" ; of the latter, " Basis calcareous ; no radii ; basis and parietes porous." 



BORRADAILE'S section approaches Acasta technically, although the form and 

 character of the shell are different. It is convenient, therefore, to call it section I, 

 retaining GROVEL'S designation for his section H. 



Chthamalus stellatus (PoLi). 



A common Indian species with a wide distribution. I have lately taken specimens 

 in the estuary of the Matla River, Lower Bengal, at a place where the water was 

 decidedly brackish. They were attached to the trunks of mangrove trees, and could 

 only have been covered by the tide during a very small part of each day. 



On the whole, the Barnacles of Ceylon, in so far as they are known, bear out the 

 remark made in the Introductory note to this paper, that every addition to our 

 knowledge of the distribution of the group tends to prove the wide dispersal of the 

 species and varieties. Of the 26 species recorded above, 3 occur in all seas, their 

 migrations being assisted by human agency ; at least 6 will probably be found in 

 every sea which is not too cold ; 4 are widely spread in the Indian Ocean and the 

 warmer parts of the Pacific, while 1 2 are only known from the Indian Ocean. Of the 

 last, however, 4 come from great depths, which have been little explored, while the 

 remaining 8 are small, inconspicuous forms. Except Tetraclita serrata, which is 

 probably found at the extreme south of the West African coast, none of the 26 species 

 are known only from the Atlantic and Pacific Oceans. It seems possible that the 

 continent of Africa has proved a barrier in some cases as regards the migration 

 westwards of Oriental species. 



