BY JOHN SHIRLEY, D.SC, F.M.S. 9 



the Middle and Upper Eocene epochs Some 



time during the Miocene epoch, the bottom of the Niim- 

 mulitic Sea was upheaved, and converted into dry land, 

 in the direction of a line extending from Abyssinia to the 

 mouth of the Ganges. 



The earth movements that severed the connection of 

 the north-west portion of the Indian Ocean with the 

 Mediterranean, caused the Red Sea to retreat to its present 

 limits, but it still maintained its union with the great Indo- 

 Pacific province, and the character of its molluscan fauna 

 remained unchanged. The Mediterranean Sea no longer 

 traversed by a warm equatorial current, lost most of its 

 genera that are typical of the Indian, Malaysian and Aus- 

 tralasian sub-regions, and, maintaining its connection with 

 the Atlantic, gave to its mollusc a a northern fades. The 

 presence of isolated species belonging to tropical genera 

 like Fasciolaria, Cancellaria, Sigaretus, Cymbium, Cyprcea, 

 Marginella, Mitra, Cassis and Pisania, is strong testimony 

 that the Meditrranean region was formerly a part of the 

 great waterway of the equatorial current. 



To the north of Australia the extension of the typical 

 molluscan fauna of Queensland is equally wonderful. The 

 Philippine Islands lie 3,500-4,000 miles from our shores, 

 yet the appearance of its molluscan fauna would be per- 

 fectly familiar to the Queensland collector. Of our 1,619 

 species of Gasteropoda, no less than 673, or over 40 per 

 cent., are known to inhabit the shores of this distant archi- 

 pelago. Of 18 additional species to our fauna, found in 

 collections sent down from Murray Island, Normanton 

 and Torres Straits, no less than half are also reported from 

 the Philippines, showing that the affinities are still greater 

 if we make the comparison between the shells of our northern 

 coast and those of this distant group of islands. Wallace's 

 Line, though it may separate land faunas of very dissimilar 

 nature, forms no hindrance to the spread of marine 

 molluscs. 



As American collectors reveal to us the wealth of 

 material which the Philippine Archipelago affords, as settle- 

 ment progresses in Northern Australia, and Avhen the 

 discovery of intermediate forms has reduced the number 



