XII RGENTINIAN AND CARIBBEAN SUB-REGIONS 373 



Monoceros. PJiotinula^ Patella^ Chiton ; Modiolarca^ Malletia^ and 

 Mulinia. Several genera characteristic of the Boreal and Arctic 

 sub-regions recur, e.g. Troi^hon^ Admete^ Margarita^ Punctarella^ 

 Ci/amlum, and Astarte. 



(6) The Argentinian^ Sub-region extends from about Cape 

 Melo in Patagonia to the neighbourhood of S. Caterina I. in 

 South Brazil (lat. 28° S.). The sub-region stands in the same 

 relation to the Magellanic, on tlie east coast, as the Peruvian 

 sub-region on the west, but, owing to tlie influence of the warm 

 Brazil current, which overpowers the colder water of the Falkland 

 branch of the Cape Horn current, it reaches a point much farther 

 south. 



The MoUusca are not well known. The prevailing genera 

 appear to be Oliva^ Olivancillaria^ Voluta, Bidlia^ Cre2)idula ; 

 Periploma^ and Lyonsia. 



(7) The Caribbean Sub-region extends from S. Caterina I. in 

 the south to Florida in the north, and includes the shores of the 

 Gulf of Mexico and the whole of the West Indies. The influence 

 of the warm Brazil current (a branch of the South Equatorial) 

 carries the range of the purely tropical species to a point much 

 farther south than is reached by the tropical species on the west 

 coast. 



The sub-region is very rich in species, especially on the coral 

 reefs of the Bahamas and N. Cuba, but the exceedingly small 

 tide-fall makes shore collecting somewhat difficult beyond a 

 certain point. The leading generas are Murex^ Purpura^ 

 Melongena^ Latirus, 3Iarginella^ Strombus^ Triton^ Cerithium^ 

 Littorina^ Nerita^ Scalaria; Tellina^ StriglUa^ Liicina, aud Ve^iiis. 

 Pleurotomaria^ a genus long regarded as extinct, has been 

 dredged alive off Tobago. 



As compared with the tropical fauna of the Old World, that 

 of the New World is poor in peculiar genera (compare p. 368). 

 The relations of this sub-region to the West African and the 

 Panamic have been already dealt with (pp. 367 and 372). 



(8) The Transatlantic Sub-region extends from Florida to Cape 

 Cod (see p. 364). In the north the limits of the sub-region are 

 distinctly marked, in the south Caribbean species intermingle. 



1 Usually known as ' Pata,2:onian,' but since the Magellanic Sub-region in- 

 cludes a considerable part of Patagonia, and since the greater part of sub-region 

 (6) lies out of Patagonia, it has been thought advisable to change the name. 



