Sentence:  But of late years extensive Tertiary deposits of Miocene age have been discovered, showing that it is not a mere congeries of volcanoes; it [Iceland] is connected with the British Islands and with Greenland by seas less than 500 fathoms deep; and it possesses a few mammalia, one of which is <WSD>peculiar</WSD>, and at least three <WSD>peculiar</WSD> species of birds. 
Meaning of the word marked with <WSD> tags:  Common or usual for a certain place or circumstance; specific or particular.