160 BALANID^I. 



yet includes a greater number of species, especially of 

 peculiar species, than the whole rest of the known world. 

 This is, probably, in chief part due to the broken nature of the 

 land, affording diversified habitats, and to much of the coast 

 being rocky. Cirripedes, from requiring to be attached, 

 cannot live where the shores and adjoining bottom are sandy 

 or muddy or formed of moving shingle ; hence, no doubt, it 

 arises, that there is such a remarkable contrast in the great 

 number of the species inhabiting the bold rocky western 

 coast of South America, and the few species living on the 

 sloping, and often sandy or muddy or shingly, eastern 

 shores of this continent. Hence, also, I believe, it is that 

 not many species have been brought from India. Coral- 

 reefs are not favorable to Cirripedes, consequently but 

 few are known to inhabit the islands of the Pacific Ocean. 

 Where Cirripedes can live, though the species in no 

 district are numerous, the individuals abound in infinite 

 numbers : I have walked over the coast-rocks of the Falk- 

 land and Chonos Islands, of Chile and Vau Diemen's Land, 

 fairly encrusted over wide spaces with a continuous layer of 

 Cirripedes, consisting of only two or three species ; in the 

 same manner as may be observed on many parts of the 

 shores of Great Britain, and, I believe, of North America. 



With respect to the effects of temperature on the range 

 of Cirripedes, no genus (having more than one species) is 

 confined to the torrid zones. Pyrgoma, from being always 

 attached to corals, is, of course, ordinarily found in the 

 hotter seas ; but one species ranges from the Cape de Verde 

 Islands in the torrid zone to the southern shores of England 

 and Ireland. Tetraclita is not found in the colder seas, but 

 is numerous in species and in individuals, on the southern 

 shores of Australia and at the Cape of Good Hope. I may 

 here add, that the two genera with the most confined ranges, 

 are Chamaesipho and Elminius ; the former has only two 

 species, one inhabiting Australia, and the other the East 

 Indian Archipelago ; Elminius has four species, confined 

 to the southern hemisphere, and inhabiting Australia, New 

 Zealand, and South America. To return to the effects of 

 temperature ; in Mr. Dana's great work on Crustacea, an 

 excellent chart is given, in which the isocrymal lines, or 



