460 TROPICAL PROVINCES OF MOLLUSCS. 



Trochita, Crepidula, Fissurella, Tornatella, Litorina, Cancellaria, Murex, 

 Triton, Colunibella, Oliva, Purpura, Mitra, Pholas, Solen, Mactra, 

 Venus, Crassatella, Nucula, Leda. 



Tropical Zone. There remains the large tropical region, which we 

 imagine to be to some extent superimposed upon the temperate life. 



The Panamic Province. Here, at the mouths of the rivers, are 

 the Potamides, Potamomya, Area, Cyrena, Auricula, while the Litorinae 

 climb trees. The shells of the shore include Columbella, Cyprsea, 

 Mitra, Purpura, Cassis, Conus, Strombus, Pleurotoma, Hipponyx, 

 Fissurella ; while among shells of deeper range are many species of 

 Murex, Monoceros, Oliva, Cancellaria, Lingula, Discina, Spondylus, 

 Cardium, Venus, Artemis, Pandora, Pholas. The narrow land of 

 Central America and Mexico makes a complete separation between 

 this region and that on the American side of the Atlantic. 



The Caribbean Province includes the Gulf of Mexico, West 

 Indian Islands, and South American coast as far as Rio. It is a 

 region fringed with coral growth. The characteristic genera include 

 Strombus, Murex, Triton, Fasciolaria, Cancellaria, Terebra, Cassis, 

 Columbella, Voluta, Oliva, Conus, v Cyprea, Litorina, Turritella, 

 Fissurella, Nerita, Calyptnea, Crepidula, Patella, Chama, Lucina, 

 Venus, Cytherea, Artemis, Lima, Area, Yoldia, Crassatella, Phola- 

 domya. 



The West African Province includes the coast within the tropics. 

 Its genera comprise Strombus, Triton, Oliva, Purpura, Murex, Terebra, 

 Mitra, Pleurotoma, Clavatula, Conus, Natica, Cyprsea, Vermetus, Ceri- 

 thium, Turritella, Haliotis, Nerita, Area, Cardium, Artemis, Cytherea, 

 Card ita. 



Indo- Pacific Province. This is an enormous area ranging between 

 Australia and Japan and Easter Island in the Pacific and the east 

 coast of Africa. This also is a region of coral reefs. A large number 

 of the characteristic genera occur fossil in the Lower Tertiary 

 strata of Europe. Among the tropical genera are Nautilus, Pteroceras, 

 Rimella, Rostellaria, Seraphs, Turbinella, Ancillaria, Magilus, 

 Neritopsis, Hemipecten, Placuna, Malleus, Vulsella, Cucullaea, 

 Hippopus, Tridacna, Cypricardia, Anatina. Among types which are 

 common to the American coast of the Pacific are Conus, Pleuro- 

 toma, Harpa, Mitra, Pyrula, Imperator, Lingula, and Discina. The 

 difference between the Mediterranean fauna and that of the Red Sea 

 is marked by some of the genera that we have named, and the 

 abundance in the Red Sea of species of others, such as Conus, Cyprea, 

 Mitra, Cerithium, Pinna, Chama, and Circe. 



Relation of Living to Fossil Faunas. If we compare these 

 faunas with each other, it would be impossible to predicate from any 

 principle recognisable in structure that some were Arctic and others 

 tropical. They rather suggest the grouping met with in different 

 geological formations ; and it is only when we begin palaeontological 

 studies from the point of view of such faunal distribution, and trace 

 its origin back to the development of existing continents, which 

 laid the newest strata bare, and drove marine life from off them, 



