222 LITTORAL DISTRICTS. 



tending to Cape Horn and the Straits of Magellan. This district probably 

 includes the Galapagos, which, as far as is accurately known, have about an 

 equal number of Peruvian and Panamic species. Many of the species gen- 

 erally credited to the Galapagos Islands are not known positively to live 

 there. The Peruvian District is remarkable for the great development the 

 Arbaciadae take, the other species being representatives of genera found in 

 the West Indian District, one of the species extending to Australia, and, as 

 I am informed by Dr. .Semper (if there is no error in the locality), two of 

 the species extend to the southern extremity of the Philippine Islands. 



Patagonian District (PL A). 



As far as known, the species of Echini of the southern extremity of 

 South America are, with few exceptions, peculiar to it. We find three or 

 four Peruvian species extending through the Straits of Magellan, and a few 

 species extending from the mouth of the La Plata on the Atlantic, around 

 the Horn to the coast of Chili, so that, to judge from positive evidence, the 

 extremity of South America forms a district lapping on the Pacific side the 

 Peruvian District (PL A), and extending on the Atlantic side to the south- 

 ern extremity of the Tropical Atlantic District (PI A), of which some of 

 the species reach the southern limit of Brazil, the coast gradually becoming 

 poorer and poorer in species as we go south from the West India Islands, 

 while towards the southern extremity of the continent a remarkable fauna 

 occurs, resembling to a certain extent the combination of species found on 

 the West Coast of Norway, in the North Atlantic District (PL B): — 



Echinus margaritaceus, Echinus norvegicus, 



Echinus magellanicus, Echinus miliaria, 



Goniociuaris canaliculata, Dorocitlaris papillata, 



Strongyloccntrotus albus, Strongyloccntrotus Drobachiensis, 



Hemiaster australis, Brissopsis lyrifera, 



Schizaster Philippii, Schizaster fragilis. 



Goniocidaris canaliculata appears, if the localities are correct, to have a 

 most extensive geographical distribution, being found at the Sandwich and 

 Navigator Islands, Natal and Falkland Islands, and with Echinocardium aus- 

 trale, which has a somewhat similar range along the southern extremities of 

 all the southern continents, anil extending even north of the equator to 

 Japan, form the characteristic species of the great Southern Circumpolar 

 Belt (PL B). 



